System and method for advancing, orienting, and immobilizing on internal body tissue a catheter or other therapeutic device

ABSTRACT

This invention provides a system and method that allows a therapeutic device, such as an atrial fibrillation microwave ablation catheter or ablation tip to be guided to a remote location within a body cavity and then accurately immobilized on the tissue, including that of a moving organ, such as the heart.

This application is a continuation of U.S. Nonprovisional applicationSer. No. 11/694,002, filed Mar. 30, 2007, now U.S. Pat. No. 8,535,304,which claims the benefit of U.S. Provisional Application Ser. No.60/744,016, filed Mar. 31, 2006, entitled INSTRUMENT TRANSPORTATION ANDPOSITIONING CATHETER, and U.S. Provisional Application Ser. No.60/868,951, filed Dec. 7, 2006, entitled ABLATION GUIDANCE SYSTEM FORMINIMALLY INVASIVE ATRIAL FIBRILLATION SURGERY, the entire disclosure ofeach application being herein incorporated by reference.

FIELD OF THE INVENTION

This invention relates to systems and methods for performing minimallyinvasive surgery and more particularly to systems and methods formanipulating therapeutic or diagnostic devices relative to organs andother tissues within a human body cavity.

BACKGROUND OF THE INVENTION

Minimally invasive surgery is becoming the preferred technique foraccessing internal organs and systems in an ever increasing number ofprocedures. Its advantages are manifold. For example, recovery times aregreatly decreased due to smaller incisions and less damage to internalstructures while gaining access to the procedure site. Also, the risk ofpost-operative infection is somewhat reduced as the internal tissues areless exposed to non-sterile environments. In addition, the procedure isoften simplified and expedited due to the lack of complex incisions andpost-procedure suturing of large incisions.

Typically, in minimally invasive procedures, instruments are insertedinto the body through steerable catheters that are initially insertedand brought adjacent to the affected organ or other procedure site.However, standard catheters do not stabilize the instrument in placewhile it is being used by the surgeon. Similarly, standard catheters canonly be coarsely steered and are not generally capable of following aserpentine path.

Some specialized mechanisms for stabilizing particular instruments havebeen devised for procedures that require a close and immobilerelationship between the instrument and the tissue being operated upon.For example, Bertolero et al., U.S. Pat. No. 6,849,075 teaches a cardiacablation device that employs a plurality vacuum orifices to hold anablation electrode in position on the heart. However, this referencedoes not provide a mechanism to move the electrode along a serpentinepath on the heart or other organ, as may be required in certainprocedures, most notably cardiac ablation, as described below. Likewise,there is no mechanism in Bertolero to bring, for example, a microwaveablation catheter into selective contact with heart tissue, as may berequired for effective ablation.

An alternate approach suggested for transporting and positioningminimally invasive surgical instruments inside the body is taught byRiviere, et al. in Published U.S. patent application Ser. No.10/982,670, using a walking robot. The robot comprises two pedestalsconnected by a spring. The distal pedestal includes a tool, typically ascope for viewing the affected area. The foot of each pedestal hasvacuum orifices, with a separate vacuum line running to each pedestal. Apair of pull wires is connected to each pedestal, allowing control ofthe relative position between the distal pedestal and the proximalpedestal. By properly sequencing the application of vacuum and thetension on the pull wires, a surgeon can cause the robot to “inchworm”across the surface of an organ. Surgical instruments are attached to thefront of the distal pedestal.

The Riviere robot employs a large vacuum region that interfaces bestwith flat organ tissue that is reasonably resilient. Under certainconditions its hold down could become dislodged or allow lateralslippage of the corresponding tool—particularly where the tissue surfaceis non-flat or roughened. To remedy such slippage, the vacuum applied toeach pedestal may be increased. However, under other conditions tissuecould be damaged by too intense local vacuum.

Moreover, these and other available devices lack the ability to performmore complex procedures, such as drug delivery, dissection and biopsy.Accordingly, it is highly desirable to provide improved mechanisms anddevices for minimally invasive surgical procedures that afford improvedfunction as well as superior mobility, immobilization once positioned,and control of an ablation device or other attached tool.

SUMMARY OF THE INVENTION

This invention overcomes the disadvantages of the prior art by providinga system and method that allows a therapeutic device, such as an atrialfibrillation microwave ablation catheter or ablation tip to be guided toa remote location within a body cavity and then accurately immobilizedon the tissue, including that of a moving organ, such as the heart. Invarious embodiments, the system and method also enables accuratemovement and steering along the tissue, while in engagement therewith.Such movement and engagement entails the use of vacuum suction,compression balloon, or microneedle structures on at least twointerconnected and articulated immobilizers that selectively engage toand release from the tissue to allow an undulating, step-by-stepcrawling/walking motion (termed a “traversing” motion herein) across theorgan as the therapeutic catheter/tool tip applies treatment (AGEdevices). In further embodiments that lack a movement capability (AIDdevices), the immobilizers allow a predetermined position for theintroduced device to be maintained against the tissue while a treatmentis applied to the location adjacent thereto. In the exemplary AGEdevices, variety of steering mechanisms and mechanisms for exposing andanchoring a catheter against the underlying tissue can be employed. Inthe exemplary AGE devices, a variety of articulation and steeringmechanisms, including those based upon pneumatic/hydraulic bellows, leadscrews and electromagnetic actuators can be employed.

In certain embodiments of an AGE or AID, the base includes one or morevacuum structures constructed with an accordion-like or bellows likeshape so as to conform to curved surfaces.

In other embodiments of an AGE or AID steering can occur based on aplurality of wires disposed about the perimeter and anchored at anappropriate location on the structure of the device. The wires areselectively tensioned or relaxed to effect steering. A control systemjoystick or other actuation structure causes tensioning and slacking ofthe wires.

In other embodiments, generally related to the AGE steering andactuation for (traversing) movement between the proximal immobilizer andthe distal immobilizer occurs based upon selective movement ofindividual bellows disposed between the immobilizers, about theperimeters thereof.

In other embodiments of an AGE, actuation between immobilizers iseffected using a flexible or rigid helical drive that is rotated by ashaft operatively connected through the device's proximal cannula with acontrol system. Where the helical drive is rigid, a universal joint orother flexible, rotating joint can be provided at a location between theimmobilizers (at the proximal immobilizer, distal immobilizer, orbetween the immobilizers). In the above helical drive implementations,steering wires extend from the proximal immobilizer to anchors in thedistal immobilizer. In another helical or linear actuation drive definea rigid structure and steering is effected by a pivoting suction cupmounted in the base of the proximal immobilizer, with which the entireAGE pivots in response to steering wires anchored in the proximalimmobilizer.

In various embodiments of an AID or AGE, a balloon or bladder is locatedwithin a lumen that carries the catheter. This balloon is connected witha pressure/vacuum source. When pressurized, the balloon inflates,thereby frictionally locking the catheter in place against axial pulloutand biasing the catheter into a bottom most position with respect to theunderlying tissue. In other embodiments, such a lock can be mechanical,such as a sliding contact surface that selectively moves into engagementwith the catheter when slid or actuated.

A variety of bellows like structures can be disposed between steerablesections of an AGE or AID. These structures can be actuated by pressureor can be non-actuatable, flexible covers with the actuation mechanism(in the case of AGEs) being another mechanism. Other actuation oractuation/steering mechanisms, with or without an outer bellowscovering, include repelling, individually energized arrays ofelectromagnets, arrays of smaller-diameter pressurized bellows, flexibleor pivotal, overlapping piston and cylinder sleeves and push-pull rodsactuated by a remote user.

In an alternate embodiment one or more immobilizers can include aplurality of tissue-engaging microneedles that are deployable fromlocations on the immobilizer base/bottom via pressurized guideways. Theneedles can be installed in a single elongated base or in a plurality ofside-by-side smaller bases so that individual sets of needles can extenddifferent distances to better conform to a curved tissue surface.

Another embodiment of a hold-down mechanism for an AGE or AID comprisesone or more inflatable, top-mounted balloons or bladders that areadapted to engage an opposing organ or tissue surface to retain the AGEagainst the underlying tissue.

An AID can also include a sliding base that moves proximally relative tofixed AID side bases that allows the enclosed catheter to be directlyexposed to the tissue. The sliding base can include a steering wireanchored therein. In this arrangement, the hold down mechanism (vacuumports, microneedles, etc) are located along the side edges of the AID'sfixed base section. The AID can also include an exposed mid section basewith thin reinforcing ribs at predetermined locations along its lengthto allow the catheter to be substantially in direct exposure to theunderlying tissue. In such an arrangement hold-down vacuum ports oranother hold-down mechanism are disposed along the side edges. An AGEcan also include a partially exposed mid section with hold-downmechanisms, such as vacuum chambers, on the sides of the exposed midsection. This exposed mid-section allows the catheter to be at leastpartially, directly exposed to the underlying tissue.

In another embodiment of an AID, the catheter is contained within aseries of incrementally spaced horseshoe-shaped hold-down segments thatare interconnected by a vacuum lumen that communicate through vacuumports in the base of each segment.

In other embodiments, the distal (or proximal) end of an AGE can includea deployable therapeutic or surgical tool. In exemplary embodiments, apneumatic, electromagnetic or mechanical actuator allows a blade orother tool contained within the immobilizer to extend into contact withtissue. In the case of a biopsy tool, tissue can be drawn into a vacuumchamber within the base of the immobilizer for it to be acted upon by ahorizontally disposed biopsy blade. Fluid-delivery hypodermic needlescan also be deployed either at and acute angle or substantially normalto the underlying tissue by driving the (flexible) needles distally downan appropriately shaped guide lumen into the tissue below.

Certain features of various embodiments described above can be combinedvariously with others described above to achieve further illustrativeembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIG. 1 is an illustration of the initial rubber catheter applicationstep in an exemplary Saltman EndoMAze Procedure (SEMAP) for ablation ofcardiac tissue in the treatment of atrial fibrillation according to theprior art;

FIG. 2 is an illustration of an ablation catheter insertion step inconnection with the SEMAP of FIG. 1, according to the prior art;

FIG. 3 is a top rear view of the subject heart undergoing a box lesionablation step in connection with the SEMAP of FIG. 1, according to theprior art;

FIG. 4 is an oblique rear side view of the subject heart showing the boxlesion ablation step of FIG. 3, according to the prior art;

FIG. 4 is a perspective view of an ablation guidance enhancer (AGE) foruse with an ablation or other therapeutic catheter or device inaccordance with a generalized illustrative embodiment of this invention;

FIG. 6 is a perspective view of the AGE of FIG. 5 in engagement with asubject heart;

FIG. 7 is a perspective view of an ablation immobilizer device (AID) foruse with an ablation or other therapeutic catheter or device inaccordance with a generalized illustrative embodiment of this invention;

FIG. 8 is a cross section of the AID taken along line 8-8 of FIG. 7;

FIG. 9 is a perspective view of the AID of FIG. 8 in engagement with asubject heart;

FIG. 10 is a an illustration of an insertion step for an exemplary AGE(or AID) through the skin and into a subject's thoracic cavity;

FIG. 11 is an illustration of the attachment of the AGE to the subjectheart;

FIG. 12 is an illustration of the movement of the AGE along the heart inaccordance with an illustrative embodiment;

FIG. 13 is an illustration of the entry of the AGE to the back of thesubject heart;

FIG. 14 is an illustration of the first turn of the AGE around thepulmonary veins of the subject heart;

FIG. 15 is an illustration of the use of multiple AGEs (or AIDs) toengage the subject heart;

FIG. 16 is a perspective view of a movable floor for exposing a portionof a catheter enclosed within the central lumen of an AGE or AIDaccording to an embodiment of this invention;

FIG. 17 is a perspective view of an inflatable bladder for displacing,toward underlying tissue, a portion of a catheter enclosed and/ormaintaining said catheter's position axially within the central lumen ofan AGE or AGE according to an embodiment of this invention;

FIG. 18 is a bottom perspective view of an AGE according to anembodiment of this invention;

FIG. 19 is an exposed cutaway perspective view of the AGE of FIG. 18;

FIG. 20A is a side cross section of a distal immobilizer of an AGEincluding an inflatable luminal catheter-holding mechanism in anundeployed/uninflated orientation according to an embodiment of theinvention;

FIG. 20B is a side cross section of the distal immobilizer of FIG. 20Ashowing the catheter-holding mechanism in a deployed/inflatedorientation;

FIG. 20C is a side cross section of an actuatable catheter-holdingmechanism in an undeployed/proximally-directed orientation according toan alternate embodiment of the invention;

FIG. 20D is a side cross section of the distal immobilizer of FIG. 20Cshowing the catheter-holding mechanism in a deployed/distally directedorientation;

FIG. 20E is a partially exposed top view of the distal immobilizer ofFIG. 20C showing the catheter-holding mechanism in a deployed/distallydirected orientation;

FIG. 21 is a top perspective view of an AID or AGE having a flexiblebellows-like, mid-section joint to assist in actuation and steeringfunctions with respect to a tissue surface;

FIG. 22 a bottom perspective view of the AID of FIG. 21;

FIG. 23 is a cross section through a mid-section bellows of an AGE orAID adapted for either pneumatic, hydraulic or cable-based steering;

FIG. 24 is a cross section through an immobilizer of the AGE or AID ofFIG. 23;

FIGS. 25-28 are each embodiments of mid-section cross sections ofpneumatic or hydraulic multiple-bellows steering mechanisms for an AGE;

FIG. 29 is a perspective view of an AGE having a helix drive movementactuation system according to an embodiment of this invention;

FIG. 30 is a cross section of the AGE taken along line 30-30 of FIG. 29showing the drive sheath;

FIG. 31 is a perspective view of a helix-drive-actuated AGE having apivoting suction cup in its proximal immobilizer according to anembodiment of the invention;

FIG. 32 is a cross section of the proximal immobilizer of the AGE takenalong line 32-32 of FIG. 31;

FIG. 33 is a side cross section of proximal immobilizer of the AGE takenalong line 33-33 of FIG. 31;

FIG. 34 is a perspective view of a helix-drive-actuated AGE having aflexible coupling for the drive within the proximal immobilizeraccording to an embodiment of this invention;

FIG. 35 is a cross section of the AGE taken along line 35-35 of FIG. 34showing the drive sheath;

FIG. 36 is a partial cross section showing an embodiment of a flexiblejoint for the helix drive for the AGE of FIG. 34;

FIG. 37 is a partial cross section showing another embodiment of aflexible joint for the helix drive for the AGE of FIG. 34;

FIG. 38 is a perspective view of a pneumatic/hydraulic piston-actuatedAGE according to an embodiment of the invention;

FIG. 39 is a partial side cross section of the AGE including the pistonassembly taken along line 39-39 of FIG. 38;

FIG. 39A is a perspective view of an electromagnetically actuated AGEaccording to an embodiment of the invention;

FIG. 39B is a more detailed fragmentary cross section of a portion ofthe electromagnetic actuator for the AGE of FIG. 39A;

FIG. 40 is a side view of an embodiment of an AGE having anelectromagnetic actuator for orienting, advancing and retracting thedistal immobilizer with respect to the proximal immobilizer;

FIG. 41 is a cross section of the AGE actuator taken along line 41-41 ofFIG. 40;

FIGS. 42-48 are schematic diagrams detailing various systems thatcombine actuation and steering between the proximal immobilizer and thedistal immobilizer of an AGE, according to various embodiments of theinvention;

FIG. 49 is a bottom perspective view of an exemplary AGE showing basicsteering and vacuum interconnections with respect to the proximalimmobilizer and the distal immobilizer;

FIG. 50 is a bottom perspective view of an exemplary AGE or AID havingan enhanced suction pad on each immobilizer for engaging rough ornon-flat tissue according to an embodiment of this invention;

FIG. 51 is a partial side view of a suction cup of the AGE or AID ofFIG. 50 approaching a non-flat tissue region;

FIG. 52 is a partial side view of the suction cup in engagement with thetissue shown in FIG. 51;

FIG. 53 is a bottom perspective view of an AGE or AID having a pluralityof enhanced suction pads on each immobilizer;

FIG. 54 is another view of the AGE or AID of FIG. 53, showing thesuction ports for each pad;

FIG. 55 is a side cross section of an immobilizer suction pad accordingto an embodiment of the invention including structures that avoidblockage of vacuum ports by tissue;

FIG. 56 is a bottom view of the immobilizer suction pad of FIG. 55;

FIG. 57 is a partial side cross section illustrating an appropriateangle for the interior wall of the suction pad of FIG. 55;

FIG. 58 is a bottom perspective view of an immobilizer for an AGE or AIDhaving an exposed central region;

FIG. 59 is an exposed bottom view of an AGE employing an array ofdeployable needles and/or microneedles as an immobilization mechanismaccording to an embodiment of the invention;

FIG. 60 is an exposed side view of the AGE of FIG. 59,

FIG. 61 is a partial front cross section of the needle deploymentmechanism taken along line 61-61 of FIG. 60 showing the needlesretracted;

FIG. 62 is the partial side cross section shown in FIG. 61 with theneedles deployed;

FIG. 63 is a somewhat schematic top view of an array of individuallymovable needle sets for use on the bottom of an immobilizer according toan embodiment of the invention;

FIG. 64 is a front cross section of the array taken along line 64-64 ofFIG. 63 in engagement with a curving tissue surface;

FIG. 65 is a side view of the array of FIG. 63 in engagement with thecurving tissue surface and detailing variable deployment of the needlesets to conform to the curve;

FIG. 66 is a somewhat schematic perspective view of an inflatablebladder on the exterior of the AGE, acting as a hold-down mechanism whenbearing against an adjacent tissue surface, according to an embodimentof the invention;

FIG. 67 is a generalized schematic diagram of a guidance system for tanAGE employing a combined bellows actuating and mechanical wire-steeringarrangement according to an embodiment of the invention;

FIG. 68 is a block diagram of the primary system components with respectto the guidance system of FIG. 67;

FIG. 69 is a somewhat schematic side view of a joystick-based steeringcontrol employed with respect to the guidance system of FIG. 67;

FIG. 70 is an exemplary control panel for a Human-Machine Interface(HMI) used in conjunction with the guidance system of FIG. 67;

FIG. 71 is a more detailed schematic view of a pneumatic or hydraulicactuator control for use with the guidance system of FIG. 67;

FIG. 72 is a perspective cross section of an immobilizer section of anAGE or AID including a movable floor that allows the inner lumen tobecome exposed;

FIG. 73 is a top perspective view of an AID according to an alternateembodiment, featuring independent immobilization segments disposed alongan exposed catheter;

FIG. 74 is a bottom perspective view an exemplary immobilization segmentof the AID of FIG. 73;

FIG. 75 is a bottom perspective view of an AID according to an alternateembodiment, featuring lateral vacuum ports along its bottom surface;

FIG. 76 is a front cross section of the AID taken along line 76-76 ofFIG. 75;

FIG. 77 is a partially exposed side cross section of the AID of FIG. 75;

FIG. 78 is a bottom perspective view of an AID according to an alternateembodiment, featuring central vacuum ports along its bottom surface;

FIG. 79 is a front cross section of the AID taken along line 79-79 ofFIG. 78;

FIG. 80 is a partially exposed side cross section of the AID of FIG. 78;

FIG. 81 is a side cross section of a distal immobilizer according to analternate embodiment, featuring a biopsy cutting tool;

FIG. 82 is a front cross section of the distal immobilizer taken alongline 82-82 of FIG. 81;

FIG. 83 is a side cross section of a distal immobilizer according to analternate embodiment, featuring a dissection tool;

FIG. 84 is a front cross section of the distal immobilizer taken alongline 84-84 of FIG. 83;

FIG. 85 is a side cross section of a distal immobilizer according to analternate embodiment, featuring an acute-angled-entry deployablefluid-delivery hypodermic needle in a retracted position;

FIG. 86 is a side cross section of the distal immobilizer of FIG. 85,showing the needle in a deployed position, engaging adjacent tissue;

FIG. 87 is a side cross section of a distal immobilizer according to analternate embodiment, featuring an perpendicularly angled-entrydeployable fluid-delivery hypodermic needle in a refracted position;

FIG. 88 is a side cross section of the distal immobilizer of FIG. 87,showing the needle in a deployed position, engaging adjacent tissue;

FIG. 88A is a side cross section of a distal immobilizer for an AGE thatenables the deployment/implantation of microneedle and microspikeimplants to tissue for interconnection by wires or tubes to a remotesystem;

FIG. 88B is a side and partial bottom view of an exemplary microspike ormicroneedle implant assembly for use with the immobilizer of FIG. 88A;

FIG. 88C is a partial cross section of an exemplary fluid-deliverymicroneedle structure that can be employed in the assembly of FIG. 88B;

FIG. 88D is a partial cross section of an exemplary electronic sensormicrospike structure that can be employed in the assembly of FIG. 88B;

FIG. 89 is a side cross section of a proximal immobilizer for use inrotating/helix drive embodiments showing the location of a flexiblejoint therefor;

FIG. 90 is a front cross section taken through line 90-90 of FIG. 89;

FIG. 91 is a front cross section taken through the interconnectingbellows between the distal immobilizer and the proximal immobilizer ofFIG. 89, facing the distal end of the proximal immobilizer;

FIG. 92 is a bottom perspective view of an exemplary distal immobilizeraccording to an alternate embodiment having an inflatable balloon withinthe inner lumen for locking a catheter in place therein externalsteering cable tie-down locations and two vacuum ports according to anembodiment of the invention;

FIG. 93 is a side cross section of the distal immobilizer taken alongline 93-93 of FIG. 92;

FIG. 94 is a front cross section of the distal immobilizer taken alongline 94-94 of FIG. 92; and

FIG. 95 is a side cross section of the distal immobilizer in accordancewith FIG. 92.

DETAILED DESCRIPTION

I. SEMAP Technique

The principles of this invention are generally applicable to the fieldof endocardial ablation. However, as will be described below, thesystems and methods described herein can also be applied to proceduresusing other types of tools, and applied to procedures involving otherinternal organs and structures in addition to the heart. In general,atrial fibrillation (AF) is a common, but not fully understooddisturbance of the heart's rhythm. It affects more than 2.2 millionpeople in the Unites States. It has been determined that altering theelectrophysiological state of the heart is useful in eliminatingunwanted electrical activity. This activity is viewed to be the primarycause of AF. A well-known procedure for reducing electrical activity isthe Cox Maze Procedure (CMP). This surgical procedure involves theinvasive entry of the thoracic cavity to expose the heart. The heart isthen dissected, and then re-sewn by sutures to disrupt unwanted pathwaysof electrical propagation. This procedure has been viewed as successfulin a large number of cases.

An alternative to the physical dissection of the heart to attain thedesired result is to generate scar tissue in a defined line around theaffected regions of the heart by either burning or freezing the cardiactissue that carries nerve connections deemed to be a cause of AF. Themost common procedure, often termed “ablation”, involves access to theinside of the heart, via for example the femoral vein. Typically, theseprocedures employ radiofrequency energy (RF) that is deliveredinternally to the left atrium in a catheter that is introduced to theheart via the femoral vein. The RF energy, which typically operates inthe microwave band, heats or burns the tissue to a predetermined depth,thereby creating a single-point lesion that cuts the nerve pathwaywithin that area of the myocardial wall. The lesions are overlappedone-upon-another until every point along the electrical pathway has beensevered. The success rate in this type of surgery has been measured tobe between approximately seventy percent and eight-fivepercent—rendering it a relatively successful outcome. There are,however, certain well-known side affects that may occur with respect tothe endocardial ablation procedures as described above. In order toavoid some of these side affects, and simplify the procedure, Dr. AdamP. Saltman, M.D. PhD. has developed and employed the Saltman EndoMAzeProcedure (also termed SEMAP). In practice, this procedure employsbilateral simultaneous thorascopy and the Flex 10® microwave energyablation catheter formerly available commercially from AFX, Inc. ofFremont, Calif., now Boston Scientific Corporation of Natick, Mass.Briefly, the procedure implicates the encircling of a portion of theheart's exterior (between the pericardium and epicardium) in the regionof the four pulmonary veins by the ablation catheter. The encircled areais then heated as appropriate to form the necessary scaring so as tosever the electrical impulses (propagated by cellular conduction) thatare believed to be the source of AF.

Referring to FIG. 1, the SEMAP procedure is initiated by introducing tothe thoracic cavity, and then wrapping two rubber guide catheters 102and 104 around the four pulmonary veins 106, 108, 110 and 112 of thesubject heart 120. The catheters can be introduced to the region viaminimally invasive techniques, which will be described further below.The two distal ends 122 and 124 of the guide catheters 102 and 104,respectively, are free until they are tied together to provide theterminal end of the chain around the heart. As shown in FIG. 2, amicrowave catheter 200 (the Flex 10® in this example) is now introducedinto the proximal end of one of the elastomeric/rubber guide catheters102. In one example another (or the same) microwave catheter may also beintroduced into the proximal end/opening of the opposing guide catheter104. In alternate embodiments, a loop around the heart using asinge-guide catheter can be provided.

Each introduced microware ablation catheter 200 comprises a series ofemitting segments that are joined by adjacent electrical connections.The emitting segments and electrical connections are collectivelyenergized by a power source located external to the patient's bodycavity. The application of energy is carefully controlled and monitoredto produce the desired level and duration of ablation heat to thepericardium.

As shown in FIG. 3, the segments lay against the heart in the region ofthe four pulmonary veins 106, 108, 110 and 112. As further viewed inFIG. 4, the ablation catheter(s) 200, which in this embodiment wrapsfully around the pulmonary veins, starts at segment 1 as shown withrespect to the guide catheter 104 and extends fully around the heart toexit at the opposing guide catheter 102.

The ablation catheters, once properly placed, are energized using knownpower application and duration to attain the desired result withoutexcessive burning into the cardiac tissue.

The above-described SEMAP technique still requires substantial effort toaffix the guide catheters at the appropriate locations with respect tothe heart. In addition there is no particular mechanism to ensure aclosely conforming relationship between the pericardial surface and thecatheters and the inherent beating of the heart renders the placementand maintaining of the catheters at the appropriate location somewhatchallenging.

II. Overview of Inventive Catheters and Introduction to Thoracic Cavity

FIG. 5 details a basic overview of an ablation guidance enhancer (AGE)500 in accordance with an overall embodiment of this invention. In thisembodiment, the AGE 500 acts as a moving system that is capable ofcontacting coronary tissue (or other internal bodily tissue) along thepericardium, maintaining close, controlled contact with the tissue,while systematically traversing the pericardium to apply the neededablation energy to sites that are desired in an incremental fashion.That is, in a typical procedure, the AGE moves to a desired location onthe heart or other organ, becomes immobilized at that position and thedevice carried within the AGE, such as an ablation catheter, applies atherapeutic procedure to the underlying tissue.

In this embodiment, the AGE comprises a proximal immobilizer 502 withvacuum hold-down capability or another type of hold-down capability (asdescribed below) along its base 504. It also comprises a distalimmobilizer 506 with similar vacuum or other remobilization capabilityalong its base 508. Notably, the distal immobilizer 506 of thisembodiment, and various other embodiments herein, includes a sloped topsurface 510 and similarly inwardly sloped side surfaces 512. Thesesloped distal surfaces assist in allowing introduction and internalthoracic movement of the distal immobilizer 506 as will be describedbelow. With reference briefly to FIG. 6, an illustration of the heart600 is shown in which the AGE 500 moves along the heart's surfacebetween respective pulmonary vessels 602 and 604 to apply neededablation energy. The ablation energy, is in particular, provided by amicrowave or similar catheter 520 that slides with respect to theproximal immobilizers 502 so as to allow the immobilizers to engaging inthe above-described traversing motion across the tissue.

As shown in FIG. 6, a bellows 620 joins the distal and proximalimmobilizers 502 and 506, thereby protecting the space therebetween fromforeign matter. The material as the AGE is one that includes minimalmoisture, so as to maximize the transmission of microwave energy withoutexcessive heating. As will be described variously below, the bottomportion of each immobilizer can be enclosed or open, at least in part toallow microwave energy to pass therethrough. To this end, in certainembodiments the bottom portion may be open to the underlying tissue ifthe material between microwave catheter and target tissuecharacteristically absorbs and dissipates an unacceptable amount ofmicrowave energy.

The AGE 500 is specifically designed to self-ambulatory, allowing it tobe introduced into the body through a small, minimally invasiveincision, as will be described below, and then move under its own power,under the manipulation of an operator, to traverse a desired area ofcontacting tissue. To, thus, summarize an example of the AGE'straversing movement: the distal immobilizer pulls the microwave catheteralong, thereby expanding the bellows relative to the proximalimmobilizer while the proximal immobilizer remains stationary(held-down) on the tissue. The distal immobilizer then becomes immobileor stationary and the proximal immobilizer is released from the tissue,and moved towards the distal immobilizer, or the bellows contracts,thereby slipping along the microwave catheter. The proximal immobilizerthen reestablishes position in new location and sequence continues ifdesired.

An alternate arrangement in accordance with this invention is theablation immobilizer device (AID) as shown in FIG. 8. The AID 700includes non-ambulatory segments 702 and 704. These segments may besteerable but do not perform the traversing function described above.The segments 702, 704 each contain at base 710 and 712, respectively,which communicates with an external vacuum source, similarly to the AGE,to apply holding suction to the underlying tissue. In use, the AID 700is typically manipulated into position using appropriate guide wires, orother like-internal-placement techniques. As shown in cross section inFIG. 8, the exemplary AID encloses a microwave ablation catheter 810,similar or identical to the Flex 10 catheter 520 described above. Thebottom edges 820 of the AID cross section may contain vacuum ports, asdescribed above, to transmit the necessary hold-down vacuum to theunderlying tissue. The central region 830 of the AID cross section isopen in this embodiment to allow direct exposure of the microwavecatheter's emission surface to the underlying tissue. With asufficiently long AID, proper steering and placement can allow an entirearea of the heart tissue to be ablated at once with the catheter axiallyfixed within the AID lumen. In other embodiments, the catheter can bemoved axially within the lumen of the AID, similar to a train beingguided along a track. Hence the AID is anchored on the tissue, and thecatheter is moved distally out of the AID's distal end to increase therange of ablation (or another procedure) by treating tissue distallyahead of the AID. To cover a longer area, the AID can be moved andimmobilized at another location on the tissue once it has treated agiven area.

Note that certain embodiments of the AID contemplate an integralsteering mechanism, typically employing a plurality of selectivelytensioned wires about the perimeter. However, in a variety ofillustrative embodiments, the AID is free of any steering function,acting as a passive, hold-down device. In a non-steerable form of theAID, other minimally invasive instruments are used to position the AID,including, but not limited to, trocars, guide catheters and steerablecatheters with lumens through which the AID is passed. The AID basicallyfunctions to piggy-back the ablation catheter or other device asappropriate. The AID can also be employed to surround any catheter-liketherapy device.

As shown in FIG. 9, the AID 700 of this example is applied to a subjectheart 900 between the pulmonary veins 902 and 904 to achieve a desiredablation in accordance with the principles of the above-described SEMAPtechnique. That is, the AID is selectively positioned so as to surroundthe four pulmonary veins and thereby generate scar tissue to block theelectrical pathways in this ringed region.

Referring now to FIGS. 10 through 14, the introduction of an exemplaryAGE to the thoracic cavity and subject heart is shown in further detailas part of a minimally invasive surgical treatment to treat AF. As notedabove, this procedure is altered appropriately to introduce anon-ambulatory AID, in that an underlying guide catheter must bedirected to the affected tissue site, and thereafter located so that theAID can take hold of the tissue on its own. Conversely, the AGE mayengage internal organ tissue at any given location thereon, and thensubsequently move to (and along) a desired location on the organ.

As now shown if FIG. 10, a trocar 1010 has been passed through anincision 1012 in the skin 1014 covering the patient's thoracic cavity1016 so that the distal end 1018 of the trocar is adjacent to the heart1020. The AGE 1030 is introduced through the trocar 1010, and nowextends out of the distal end 1018. The AGE catheter's proximal end1032, which typically includes a covering cannula, extends out of theflared proximal end 1034 of the trocar. The proximal cannula (1032) canextend from the proximal face of the proximal immobilizer back to aremote control system and appropriate power sources, as describedfurther below.

Typically, the AGE or AID in this and other embodiments described hereindefines an external shape capable of fitting within a generallycylindrical outline of approximately 10 to 14 millimeters in diameter soas to fit smoothly through a standard surgical cannula, which istypically approximately 15 millimeters in internal diameter.

The AGE 1030 of this embodiment includes a proximal immobilizer 1040, adistal immobilizer 1042, an interconnecting bellows 1044, andappropriate steering wires 1046 that surround the central axis 1048 ofthe AGE 1030. Briefly, in operation, a vacuum is applied to eachimmobilizer 1040 and 1042 to cause the immobilizers to selectivelyengage the underlying (heart) tissue. This engagement is shown generallyin FIG. 11. As detailed therein, the distal and proximal immobilizers1042 and 1040 have now engaged the tissue 1110. The microwave ablationcatheter 1060 is contained within the distal and proximal immobilizers1042, 1044, and extends proximally through the trocar 1010. The catheter1060, which may also be enclosed within the proximal cannula 1032, isready to be energized when the distal and proximal ends are positionedat the appropriate site on the heart 1020 for ablation. Thereafter, theAGE 1030 is directed by the practitioner to walk or perform thecrawling/traversing motion across the heart surface, sequentiallyimmobilizing itself by activating the vacuum in both immobilizers andthen energizing the catheter for the prescribed time period so as togenerate a scar tissue through selective heating. Progress of thecatheter as it crawls along the surface can be tracked in a variety ofways. In general, the catheter and/or the AGE (or AID in otherembodiments) can include radio opaque inserts and/or fillers that enableit to be easily tracked using scanning techniques such as fluoroscopy.Ultrasound and/or other internal imaging techniques can be employed. Inalternate embodiments, a second endoscope can be inserted into thethoracic cavity to visually monitor the moving AGE's progress.

As shown in FIG. 12, using the proximally located control system, thedistal immobilizer 1042 of the AGE 1030 is caused to extend outwardly(arrow 1210) by action of the bellows 1044 or another actuation device,as described below. In operation, the distal immobilizer 1042 extendsoutwardly after the local vacuum to its base has been deactivated.Meanwhile, the vacuum on the proximal end 1040 is maintained.Subsequently, the proximal immobilizer 1040 is brought forward along thepath of travel by releasing its vacuum and contracting the bellows 1040.At this time, the distal immobilizer's vacuum is maintained so that itmaintains its hold against the tissue 1040. This traversing technique ofcrawling around the heart's surface allows each length of targetedtissue along the pathway to be incrementally radiated with microwavesand, thereby, ablated as appropriate.

To access more-remote portions of the heart, a trocar 1310 can beinserted through a backside incision 1320 as shown in FIG. 13. The AGE1030 moves along the rear of the heart 1020 as shown to apply ablationenergy to rear portions of the heart 1020, behind the pulmonary veins1330, 1332, 1334 and 1336. With reference now to FIG. 14, the walkingaction of the AGE 1030 allows it to move around the veins as shown. Itshould be clear that a variety of introduction techniques are expresslycontemplated herein. These techniques will depend, in part, upon whetheran AGE or AID is being employed.

As shown in FIG. 15, it is contemplated that a larger-diameter trocar1510 can be used to introduce multiple AGE or AID units 1520, 1530 and1540 somewhat simultaneously to the treatment area of the heart 1550.Each of these devices can be energized in turn, or simultaneously, toachieve the desired ablation of the underlying tissue.

III. Immobilization/Hold-Down Mechanisms

One form of AID that can be implemented in accordance with theembodiment of FIG. 15 (or other embodiments herein) is shown in FIGS. 16and 17. The depicted AID 1600 of this embodiment includes an open,inverted-U-shaped top section 1610 having a pair of outwardly extendedbasis 1620 that provide a somewhat “Omega” outline to the device'scross-section. The interior lumen 1630, is sized and arranged toaccommodate a microwave ablation catheter, or another similarlysized/shaped catheter. To facilitate insertion the catheter's bottomside 1638 remains enclosed. The center of the catheter's bottom 1638comprises a slidable bottom member 1640 that moves axially (double arrow1642) as desired. It is controlled from outside the patient's body bygrasping, and withdrawing proximally, a proximal end of the sliding base1640 (or an interconnected element).

The catheter 1710 is shown inserted through the lumen 1630 in FIG. 17.The catheter 1710 extends beyond the distal end 1720 of the AID 1600 inthis example, but can reside flush with or internal to the AID inalternate arrangements. The base 1640 has been removed to allow thecatheter to be exposed relative to the underlying tissue. As describedbelow, a variety of mechanisms can be used to share and steer thedevice. To facilitate shaping and steering, a series of V-shaped cutouts1650 are provided along the base 1620. These cutouts 1650 providestress-reliefs that enhance the bendability/steerability. In general,the cross section shape of this AID 1600 defines an “omega” shape withan inverted-U-shaped top 1610 and opposing, outwardly extending bases1620. The omega cross section is inherently stiffer in the planeparallel to the bases 1620 on the tissue interface surface. Based uponthis geometry, the depicted V-shaped 1650 cutouts provide a desiredselective reduction in stiffness at their vertices of the, inducing thecatheter to bend in the region of the cutouts 1650.

Note that the sliding central base 1640 rides within a corresponding keyslot 1660 formed into each side of the device's interior wall. These keyslots 1660 ensure that the base 1640 does not become inadvertentlydislodged. As will also be described below, the base 1620, or anotherportion of the device 1600 includes a plurality of vacuum ports that areselectively operated to cause the device to become firmly adhered to,and immobilized upon, the underlying tissue when the vacuum is applied.

While discussed further below with respect to additional featuresaccording to embodiments of this invention, this embodiment of the AID1600 includes an inflatable bladder or balloon 1670 near its distal endat the top of the interior lumen 1630. This feature is also applicableto other AID/AGE embodiments herein. The bladder 1670 communicates witha pressure source that can be routed through a lumen 1672 (shown inphantom) in the top wall of the device proximally to the control systemthat is external of the patient's body. When uninflated, the balloonallows passage of the catheter 1710 therethrough. When subsequentlyinflated, as shown in FIG. 17, the catheter is forced downwardly throughthe now opened bottom slot, and into closer proximity to the underlyingtissue. This arrangement can improve the efficiency of ablation in thisembodiment. The length of extension of the bladder 1670 along thelongitudinal/axial direction of the AID 1600 is highly variable anddepends, in part upon how long a section of catheter 1710 is to bedisplaced toward the underlying tissue.

Reference is now made to FIGS. 18 and 19, which show an exemplary AGE1800, respectively, in full external bottom view, and also in partialbottom cutaway. The microwave ablation catheter 1810 can be seen clearlypassing through the AGE structure. A proximal cannula 1820 is providedahead of the actual AGE 1800 to encase and guide the catheter 1810 andany surrounding wires, cables, lumens, etc., which are used to controland monitor the AGE. The cannula 1820 can extend fully to the actuationand/or guidance control system, which will be described further below,or the cannula can be truncated as appropriate. In most embodiments, thecannula 1820 extends the full distance proximally to the guidancesystem.

A set of at least three, circumferentially spaced steering wires 1830extend through appropriately positioned lumens 1832 in the cannula 1820,and thereafter into each of the proximal immobilizer 1840 and distalimmobilizer 1842. Typically the steering wires pass slidably through theproximal immobilizer 1840 and are distally anchored in the distalimmobilizer 1842. A flexible bellows 1850 joins the proximal immobilizer1840 and distal immobilizer 1842. This bellows can be sealed to thedistal face 1844 and the proximal face 1846 of the distal immobilizer soas to allow an applied vacuum to cause the bellows to contract andthereby move immobilizers toward each other, or an applied pressure willmove the immobilizers away from each other. This is one more possiblemechanism for actuating movement in the AGE, although a plurality ofalternate actuation mechanisms are described below. In alternateembodiments, the bellows 1850 is not the actuation mechanism and acts asan outer cover to protect underlying steering and actuation components.In certain non-bellows-actuating embodiments, this outer bellows can beomitted entirely.

The base 1860 and 1862 of each immobilizer 1840 and 1842, respectively,includes the central cavity or chamber 1864 and 1866, respectively. Eachvacuum cavity 1864, 1866 comprises a vacuum chamber that is designed tobear against the underlying tissue. In this embodiment, a respectivepair of vacuum ports 1866 is provided to each immobilizer's vacuumcavity 1864, 1866. Each pair of vacuum ports 1866 is connected to arespective vacuum source lumen that extends proximally to the controlsystem, one of which lumens 1910 is shown, extending through the AGE1800 to the distal immobilizer 1842. Each vacuum source lumen extendsrespectively to each of the immobilizers, thereby allowing eachimmobilizer's applied vacuum to be individually controlled. This in-partallows the crawling/traversing-type movement described above, as eachimmobilizer can be individually anchored to the tissue, while the othermoves along the tissue.

As discussed above, within the bellows 1850 a variety of “actuation”mechanisms can be provided that allow the proximal immobilizer 1840 tomove toward and away from the distal immobilizer 1842, thereby providingthe desired movement across the surface. Likewise, the steering wires1830 each selectively transmit tension between the proximal and distalimmobilizers allowing distal immobilizer to deflect relative to theproximal immobilizer. As it is deflected at an angle, the distalimmobilizer can be pushed forward by the actuation function, andthereafter secured to a new location. In this embodiment, each baseincludes a pair of linearly oriented electrodes 1870 and 1872 that canmeasure electrical conductivity, and thereby allow the user to confirmwhen a given base is in firm contact with an underlying tissue surface(among other readings). Transmission of electrical impulses between theelectrodes 1870 indicates that both electrodes are contacting thetissue. In particular, these electrodes 1870 can be used to verify thata therapeutic ablation has been applied by determining if the appliedablation adequately disrupted an electrical test signal transmitted bythe control system between the two electrodes along the contactedunderlying tissue therebetween. In this embodiment, because the materialof the AGE is relatively transparent to microwave energy (a siliconeformulation, for example), the microwave energy passes through the AGEand heats the underlying tissue, which is saturated with moisture, andthereby increases in temperature in response to the applied microwaveenergy. As noted above, various vacuum conduits, electrical wires, andother needed components pass through appropriate lumens along the AGE1800, and proximally back through the cannula 1820.

Various embodiments of the AGE shown herein include a central lumen thatis particularly sized and arranged to receive a therapeutic catheter.The lumen can be sized to closely conform to the shape of the catheter,or it can be somewhat oversized, allowing the catheter appropriate playwithin the device. The catheter shaft can be allowed to slide freelywithin the AGE or it can be anchored at some location along the AGEand/or proximal cannula. FIGS. 20A and 20B detail a mechanism forlocking the catheter axially in place with respect to the AGE. Thismechanism is structured and functions similarly to that of FIGS. 16-17above. The mechanism is shown within an exemplary distal immobilizer2000, which can include a variety of actuation, steering andimmobilization systems in accordance with various teachings of thisinvention. This mechanism can also be applied to the proximalimmobilizer or along the device cannula where appropriate.

As shown in FIG. 20A, the distal tip 2002 of the immobilizer is angledfor improved insertion as discussed above. The tip 2002 in thisembodiment, and various other embodiments, encloses the distal end ofthe immobilizer lumen 2003, and includes a front wall 2004 that isinternally shaped to approximately conform to the distal end 2006 of acatheter 2010, which is also angled. A catheter with a non-angled tipcan be used in alternate implementations.

As shown further in FIG. 20A, a deflated balloon or bladder 2011 islocated on the inner top wall 2012 of the immobilizer lumen 2003. Thisballoon 2011, like others described variously herein can be constructedfrom any acceptable, pliable and expandable/elastic, thin-walledmaterial. The balloon communicates with a lumen 2014 that interconnectswith a pressure and vacuum source at the control system. As shown, avacuum (proximal arrow 2016) has been applied through the lumen 2016 toevacuate and deflate the balloon 2011. This deflation creates an opengap 2018 between the top 2020 of the catheter 2010 and the balloon. Thisallows the catheter 2010 to move freely within the lumen 2003.

As shown in FIG. 20B, a pressure (distal arrow 2022) is now applied tothe lumen 2014 and balloon 2011. This pressure causes the balloon 2011to inflate as shown. The inflation causes the balloon to fill the gap2018 and apply downward pressure to the catheter that forces (arrows2023) it against the bottom wall 2024 of the immobilizer 2010. Thisengagement, as well as engagement with the balloon generates holdingfriction that resists axial (along the axis 2026) pullout of thecatheter 2010 from the immobilizer 2000. This arrangement alsoadvantageously moves the catheter to its bottommost orientation so thatthe distance from the underlying tissue is minimized and predictable.

As described herein, many functions, such as steering and actuation canbe implemented using mechanical push-pull mechanisms, which are eithermanually or mechanically (using electrical, pneumatic or hydraulicactuators) actuated by the user at the control system-end. FIGS. 20C-20Eshows a version of the distal immobilizer 2050 that houses the catheter2010 similarly to the immobilizer 2000 above. This immobilizer 2050includes a mechanically actuated, push-pull catheter locking mechanismaccording to an alternate embodiment of this invention. The top wall2052 of the immobilizer 2050 defines a gap 2050 that allows some lateralmovement in the catheter 2010 with respect to the catheter lumen 2056.

A sliding base 2058 having an elastomeric contact surface 2060 ridesaxially along the top wall 2052. The sliding base 2058 is interconnectedwith a flexible shaft 2062 that extends proximally back through theproximal immobilizer (proximal components not shown), and back throughthe cannula to the control system. An appropriate lumen in the proximalimmobilizer and cannula can be provided to guide this shaft 2062 and anyother push-pull flexible shaft(s) described herein. Within the top sideof the base 2058 and/or shaft 2062 is defined a detent 2064. The detentis adapted to ride over a domed locking projection 2066 formed in thetop wall 2052 of the immobilizer lumen 2056. In a retracted position asshown in FIG. 20C, the flexible shaft 2062 positions the base 2058proximally of, and out of engagement with the projection 2066. In thisposition, a gap 2070 exists between the top 2012 of the catheter 2010and the bottom of the contact surface 2060 of the locking mechanism.

When the catheter is appropriately axially positioned within the lumen2056, the shaft 2062 is slid distally (arrow 2072) by the user. Note inFIG. 20E that the base includes side wings 2080 that are adapted to rideon slots 2082 formed in the immobilizer's top. This sliding actioncauses the base 2058 to ride over the projection 2066 until the detent2064 comes in to engagement with the projection 2066 as shown in FIGS.20D and 20E. In this position, the gap 2070 is closed and theelastomeric contact surface 2060 is elastically deformed as it bearspressurably against the top 2012 of the catheter. This provides africtional hold against the catheter 2010, and also causes the catheterto bias (arrows 2074) against the bottom 2076 of the immobilizer 2050.The pressure is sufficient to resist axial pullout of the catheterrelative to the lumen 2056. This mechanism can alternately be applied tothe proximal immobilizer or cannula. To release the holding pressure,the user draws the shaft 2062 distally to move the base 2058 out ofengagement with the projection 2066. This again defines the gap 2070between the catheter top 2012 and the contact surface 2060.

It should be clear that a variety of mechanisms can be adapted to lockthe catheter with respect to the AGE or AID lumen. These mechanisms canbe driven by a variety of motive forces including, but not limited to,manual force, electromagnetics, pneumatics and hydraulics. In someembodiments, a catheter may include an integral detent, or other catchstructure, that engages a selectively deployed latch to effect holding.

As described above, both the AGE and AID implementations describedherein include a variety of port assemblies along their base in order totransmit a vacuum to the underlying tissue. As shown in FIG. 21, anexemplary AGE 2100 includes an omega-shape body 2110 with a proximalportion 2112 and a distal portion 2114 that each houses a catheter 2120.A bellows-like region 2130 is provided between the proximal and distalsections 2112 and 2114. In an AID configuration, this accordion-likebellows shape allows bending of the sections 2112 and 2114 relative toeach other for guidance and steering using, for example, embeddedsteering wires 2140. As shown further in FIG. 22, the bottom side/base2210 of the device 2100 includes a series of ports 2220, which areshaped generally as elongated ovals in this embodiment. Alternativelythe ports 2220 can be round, or any other acceptable shape. The depictedports 2220 are disposed in a staggered arrangement along each respectivebase side 2230 on opposite sides of the central region 2340 thatdirectly underlies the catheter 2120. The base sides 2230 formoutwardly-extended flanges (the bottom of the “omega”) that allow thehold-down vacuum to be transmitted to the base (and hence, transmittedto the underlying tissue) over a significant surface area while stillallowing the central lumen to remain largely exposed to the underlyingtissue when desired without interfering ports and other structures. Inthis embodiment, additional side ports 2260 are also provided along thebellows region 2130 to allow to be secured to the tissue for furtheroverall stability.

As described herein certain embodiments of the AID and AGE allow forcontinually opened, or selectively opened regions on the bottom, toafford direct exposure of the catheter to the underlying tissue. Inother embodiments in which the bottom is substantially (or fully) closedthis bottom region should be constructed from a material with highmicrowave transmissivity.

In an alternate AGE configuration, the distal and proximal ports can beseparately accessed by independent vacuum sources to thereby allowself-ambulatory, traversing or crawling motion. Alternatively, all portscan be connected to a common vacuum source to allow hold-down of theentire device at once in an AID configuration. In a further alternateembodiment, in an AID configuration, the distal portion 2114 can beconnected to a separate vacuum source so as to allow it to steer, whileat least a portion of the AID (such as the proximal portion 2112)maintains vacuum engagement with the underlying tissue. In generalhowever (and as noted above), the various AID embodiments herein aretypically implemented as a non-steering, passively applied hold-downdevice, which piggy-backs the microwave or other type of catheter.

IV. Actuation of Immobilizers to Effect AGE Movement

A variety of techniques can be used to actuate movement so as togenerate the desired traversing motion in an AGE. These techniques caninclude hydraulic and pneumatic actuators, screw drives, mechanicalpush-pull mechanisms and electromagnetic drives. Two basic AGE pneumaticbellows actuation embodiments are shown in cross section, FIGS. 23 and24 is now described in further detail. With reference first to FIG. 23,the immobilizer body 2310 is shown with a cross-section taken throughand interconnected bellows 2320. This bellows 2320 is sealed against theproximal immobilizer 2340 and also against distal immobilizer (notshown) to prevent gas leaks. The proximal immobilizer channels a pair ofpressure lumens 2350 into the bellows 2320. A set of steering wires 2352reside outside the bellows, exposed to the environment. A pair of vacuumchannels 2354 also pass selectively into each of the immobilizers tocontrol the vacuum within the central vacuum base 2356 of eachimmobilizer. A central lumen 2358 is provided for the catheter. Byapplying positive and/or negative pressure to the lumens 2350, thebellows can be extended or contracted, respectively, allowing theproximal immobilizer 2340 to move (away or toward, respectively)relative to the distal immobilizer. While not shown, the immobilizerscan be joined by a second outer sheath with a bellows-like geometry thatcovers the exposed steering wires and other structures, which extendbetween the two immobilizers. This assists in preventing the tangling orclogging of these components in bodily tissue.

The embodiment of FIG. 24 differs from that of FIG. 23 in that thesteering wire lumens 2410 reside within the enclosure of the bellows2420. The pressure vacuum lumens 2430 provide needed pressure to expandand contract the bellows 2420. A pair of vacuum immobilizer lumens 2450selectively provide a vacuum hold-down force to each of the vacuumchambers 2460. These lumens 2450 are isolated from the environment ofthe bellows so as to maintain a separate vacuum state for use at thevacuum chambers 2460 of the immobilizers. An internal lumen 2470 for thecatheter is provided above the vacuum chamber 2460. The steering wirelumens 2410, must be appropriately sealed relative to the volume definedby the bellows 2420 so that vacuum pressure is not lost due to the factthat they pass through the otherwise sealed area or the bellows.

In alternate embodiments, both actuation of movement between theproximal and distal immobilizers and steering therebetween can beeffected using a single force, namely pneumatic or hydraulic pressure.As shown in FIG. 25, a distal immobilizer 2510 is provided with threeindependently operated bellows 2520, 2522 and 2544. A pair of separatevacuum lumens 2530 are also provided to impart the necessary hold-downforce to the vacuum chamber 2532. A central lumen 2540 for a catheter2542 is also provided. By selectively actuating, with appropriatepressure and/or vacuum each of the bellows, the distal immobilizer canbe moved in any direction, including forwardly at an appropriate angle,with respect to the proximal immobilizer.

FIG. 26 shows the distal end of an immobilizer 2610 that includes fourbellows 2620, 2622, 2624 and 2626 that are arranged appropriately aroundthe external perimeter 2628 of the immobilizer. Likewise, a catheter2630 is provided within an appropriate lumen 2632 and a pair of vacuumlumens 2640 supply each of the vacuum chambers 2642 to provide hold-downforce.

While the bellows in FIGS. 25 and 26 are circular and, generally,concentric about their appropriate vacuum lumens 2570 and 2670,respectively, it is contemplated that the bellows can provide increasedsize/volume by providing them with an elongated cross-section. In FIG.27, the proximal immobilizer 2710 includes a pair of somewhatovular-cross-section bellows 2720, 2722, 2724 and 2726 located in anefficient arrangement about the perimeter 2728 of the immobilizer 2710.Each of these bellows is fed by an appropriate vacuum lumen 2770 that,like other bellows and lumens described herein, is in sealedcommunication with the proximal control system. Through use of theappropriate valves, each bellows can be selectively operated to generatea positive pressure and/or vacuum as appropriate to steer and/or advancethe distal immobilizer with respect to the proximal immobilizer. Asimilar elongated-cross-section-bellows arrangement is shown for theimmobilizer 2810 of FIG. 28. Three bellows 2820, 2822 and 2824, sizedappropriately, are provided about the perimeter 2828 of the immobilizer.Note that, in each of these embodiments, the lumen that transmits fluidto and from each bellows extends generally through the proximalimmobilizer while the corresponding mating connection and the distalimmobilizer is typically lumen-free, with the bellows simplyestablishing a sealed connection against the proximal end of the distalimmobilizer (not shown). In this manner fluid is either withdrawn fromthe bellows chamber or forced into the bellows chamber without beingpassed into the distal immobilizer.

One advantage to each of the above-described small-diameter, independentbellows is that they may require less total airflow/fill time to effectactuation over a given distance. This is because they collectivelyoccupy a smaller overall volume than the larger-volume bellows describedabove with reference to FIGS. 23 and 24.

An alternate type and embodiment of actuating/advancing mechanism isshown in FIGS. 29 and 30. The depicted AGE 2910 consists of a proximalimmobilizer 2920 and a distal immobilizer 2922 of a general size andshape similar to those described above. The bellows between theimmobilizers 2920 and 2922 has been omitted from FIG. 29 for clarity.This bellows 3010 is shown in cross-section in FIG. 30. As describedbelow, the bellows 3010 is only meant to provide acompressible/expandable cover the internal components betweenimmobilizers in this embodiment, and not to provide an actuationmechanism.

In this embodiment, the proximal immobilizer 2910 and distal immobilizer2922 are interconnected by steering wires 2932. These wires 2932 can beindependently tensioned to allow the distal immobilizer 2922 to moveangularly with respect to the proximal immobilizer 2920. Vacuum lumens3020 pass between the proximal immobilizer and the distal immobilizer toallow the proximal immobilizer 2920 to be selectively provided withhold-down vacuum force relative to the distal immobilizer 2922 asdesired. The catheter 2930, which spans between the proximal and distalimmobilizers, is located to direct its energy downwardly through thebase (3030 in FIG. 30).

Notably, at the top end of both the proximal and distal immobilizers ismounted an interconnecting flexible helical drive 2950. The helicaldrive includes a flexible drive shaft 2952 that extends outwardlythrough the cannula 2954 and back to a rotating mechanism on theguidance system. The flexible helical drive screw 2950 can beconstructed from any resilient acceptable polymer or flexible metallead. In this embodiment one end of the drive 2950 is rotatably fixed,and the opposing end is allowed to rotate within a threaded nut. In thisembodiment the nut 2970 is shown (in phantom) embedded in the proximalend of the distal immobilizer 2922. As the helical drive 2950 rotates itrotates through the fixed nut, thereby moving the proximal immobilizertoward and away from the distal immobilizer. A channel 2972 (shown inphantom) is provided distally of the nut to allows run-out room for theadvancing drive screw 2950 as the proximal immobilizer drives distallytoward the distal immobilizer. The proximal immobilizer in this andother embodiments slides freely along any distally connected lumens,steering wires and the catheter itself 2930 so that it is free to movetoward and away from the distal immobilizer. Rotation between the twoimmobilizers 2920 and 2922 is generally restricted as the screw 2950rotates due to the triangular shape of the catheter 2930 and theconforming lumen 3050 (FIG. 30). Because the catheter is somewhatflexible, it still allows the needed steering between immobilizers,however. In alternate embodiments, flexible, sliding guide rods can beused to restrict rotation of one immobilizer with respect to the other.These rods can be located separate from other connections between theimmobilizers (lumens, steering wires, etc.), or the flexibleanti-rotation guide rods can slidably encase some these interconnectingelements between the immobilizers (for example the steering wires).

In an alternate implementation of the helical drive screw of FIGS. 29and 30, both ends of the screw can include nuts, with an appropriatestop mechanism to prevent over-extension of the ends with respect toeach other.

The helical drive mechanism of FIGS. 29 and 30 generally allows thedistal and proximal immobilizers to be moved toward and away from eachother (double arrow 2960) based upon rotation (double curved arrow 2962)of the shaft 2952. Because the drive screw 2950 is flexible, it allowsthe steering wires 2932 to bend the distal immobilizer 2922 with respectto the proximal immobilizer 2920, thereby affording steerability as wellas linear actuation.

It is contemplated that the above-described helical drive and otherhelical/rotationally actuated drives described herein can be driven by astepper, servo, or other type of motor, typically located at theproximal control system. The encoder or other motion control device canemployed using the rotational or linear feedback data to provideposition feedback information in connection with the immobilizer. Suchinformation can be displayed to the user and/or used to provideautomatic control functions to the actuation of the AGE.

Yet another helical-screw actuation mechanism for an AGE is shown inFIGS. 31-33. The AGE 3110 in this embodiment includes a cannula 3112,proximal immobilizer 3114 and distal immobilizer 3116. The helical drivescrew 3120 in this embodiment is rigid, rather than flexible. The screw3120 engages a nut embedded in the distal immobilizer (not shown)similar to the embodiment of FIGS. 29-30 described above. Hence, theproximal immobilizer 3114 and distal immobilizer 3116 may only movetoward and away from each other in a linear manner (straightdouble-arrow 3130). Steering of the entire AGE in a desired direction iseffected by rotating the structure about a pivoting vacuum plate 3140located at the base of the proximal immobilizer 3114. The vacuum plateis adapted to engage the tissue and acts as the proximal immobilizer'sprimary hold-down mechanism with respect to underlying tissue. Whenengaged with tissue, and while the distal immobilizer's vacuum isdisengaged, the structure is free to rotate about an axis 3142 throughthe center of the vacuum plate 3140.

A set of four steering cables 3150 are located about the perimeter ofthe proximal immobilizer 3114. These steering cables 3150, byselectively tensioning and/or releasing them, allow the proximal end tobe manipulated with respect to the axis 3142. As such, the entire AGEend (both proximal and distal immobilizers) can be moved in anappropriate direction (double curved arrow 3160). The pivoting vacuumplate 3140 is fed by a separate vacuum line 3170 that extends back tothe guidance system, and is engaged when the proximal end is held downto the tissue. Pivoting is enabled by forming a seal between the vacuumplate and end of the line 3170 that allows rotation of the plate 3140with respect to the line end. Appropriate lip structures formed betweenthe line and plate, and user of polymers in their construction havinglow-friction properties can be used to create a rotatable seal in amanner known to those of ordinary skill. Each steering cable is anchoredwith an anchor well 3320, as shown in FIG. 33 near the distal face 3330of the proximal immobilizer 3114. Conventional vacuum lumens 3230 areprovided in both the proximal immobilizer 3114 to direct appropriatevacuum pressure to the distal immobilizer 3116 so as to generate desiredhold down force as needed.

Referring now to FIGS. 34-37, another embodiment of ahelical-drive-actuated AGE 3410 is shown. The AGE 3410 includes aproximal immobilizer 3412 and distal immobilizer 3414. The helical drive3420 is rigid in this embodiment, but is secured along the distal faceof the proximal immobilizer 3412 by a flexible rotating joint 3430 thatinterconnects with a drive shaft 3432. As shown in the cross section ofFIG. 35, taken through the omitted outer sheath, a set of steering wires3520 surround the perimeter and allow the distal immobilizer 3414 tosteer angularly (double-curved arrow 3450) relative to the proximalimmobilizer 3412 about the flexible joint 3430. To effect this steerablemotion, the steering wires 3520 move freely through lumens in theproximal immobilizer, and are anchored in the distal immobilizer. Vacuumlumens 3530 are provided in both the proximal immobilizer, and thedistal immobilizer, both being in communication with the control system,and enabling the proximal and distal immobilizers to be separately helddown to the tissue by applied vacuum as desired.

With further reference to FIG. 36, an embodiment of a flexible joint3430 for use in the AGE of FIG. 34 is shown. This joint extends throughthe distal face 3610 of the proximal immobilizer from the rigid helicaldrive screw 3420. In this embodiment, the nut is located within thedistal immobilizer. It is contemplated in alternate embodiments that theflexible joint 3430 can be provided at the proximal face of the distalimmobilizer. In that case, the nut would be provided within the proximalimmobilizer. In the depicted flexible joint 3430 of FIG. 36, therotating, flexible components consists of a socket 3620 that engages acorresponding ball on the end of the drive shaft 3630. Such a ball andsocket arrangement allows for appropriate rotation of one member withrespect to the other, at angular deflections from linear. Theconstruction of such a ball and socket joint and should be clear tothose of ordinary skill.

In an alternate embodiment of the flexible joint 3430, shown in FIG. 37,the end of the helical drive 3420 includes a slotted clevis 3720 thatengages an overlapping universal joint base 3722 with rotating pins 3724passing out of the base 3722 and into opposing sides of the overlappingclevis 3720. This arrangement is similar to the universal joint found inmost automobiles and its construction known to those of ordinary skill.

Another inventive type of pressure-driven AGE articulation system,according to an alternate embodiment, is shown in FIGS. 38 and 39. TheAGE 3810 consists of a proximal immobilizer 3812 and a distalimmobilizer 3814 that are joined by steering cables 3820 that areconfigured and operate similarly to those described above. That is, thecables move freely through the proximal immobilizer 3812, and areanchored in the distal immobilizer 3814 and tensioning of selectedcables causes the distal immobilizer to point ant a non-linear(off-axis) angle with respect to the proximal immobilizer. As shown inthe partial cross section in FIG. 39, the distal immobilizer 3814includes a rigid or semi-rigid sleeve 3920 that extends proximallytoward the distal face 3922 of the proximal immobilizer 3812. A nestedsleeve 3930 extends into the overlapping sleeve 3920. The nested,smaller diameter sleeve 3930 is open at its distal end 3934 allowingpressure and/or vacuum to fill the space within the overlapped sleeves.The outer diameter of the nested sleeve 3930 is closely matched to theinner diameter of the overlapping sleeve 3920, or one or more sealingrings are disposed between the sleeves. In either arrangement, arelative gas seal is created between the two overlapping sleeves 3920and 3930. By alternately pressurizing or evacuating the lead pipe 3952,the sleeves are moved away or toward each other, respectively.

A gap 3940 is formed in the face 3922 of the proximal immobilizer aroundthe sleeve 3930. This gap is sufficient to allow a degree of angularsteering movement (double-curved arrow 3940) of the sleeves 3920 and3930 with respect to the face 3922. In addition a flexibleaccordion-like bellows 3950 is provided on the lead pipe 3952 of thesleeve arrangement to allow the sleeve arrangement to pivotally bendalong the bellows during steering. Hence, the distal immobilizer 3814can pivot or steer with respect to the proximal immobilizer 3812 withoutbinding up the two overlapping sleeves. This lead pipe, 3952 extendsback to a pressure/vacuum source at the control system. These sleevesact, in essence, as a bi-directional piston. Because there is a gap3940, the steering cables are allowed to steer the distal immobilizerwith respect to the proximal immobilizer and linear movement (doublearrow 3954) is accomplished using the sleeve arrangement.

FIG. 39A shows an embodiment of an AGE 3960 based upon a linearactuator, which includes a proximal immobilizer 3962 and distalimmobilizer 3964 that are actuated based upon an electromagneticactuation assembly 3966. The AGE 3960 in this embodiment includes acatheter 3968 in accordance with any of the embodiments describedherein. The AGE is steered by a plurality of steering wires 3970 thatextend between the proximal immobilizer 3962 and the distal immobilizer3964. A variety of steering mechanisms can be used in alternateembodiments, as described above. The proximal immobilizer 3962 isattached to a proximally directed cannula 3971. The cannula extendsapproximately (arrow 3972) back to the control system. It carries theelectrical wires for powering the actuator, and other components used tooperate the AGE movement mechanism.

The actuation assembly is shown in partial cross section in FIG. 39B.Generally, it consists of a linear motor winding (wire coils) 3980. Thecoils surround a shaft 3982 that extends between the proximalimmobilizer and end point 3984 that is spaced remote from the proximalface 3986 of the distal immobilizer 3964. A second shaft 3988 is fixedto the proximal face 3986 of the distal immobilizer 3964. The secondshaft 3988 carries magnets 3990 or another form of magnetic material. Itis nested, and rides within, the larger diameter shaft 3982. When thecoils are energized with one of two respective polarities, the shafts3982, 3988 collectively move in each of two respective directions,depending upon the polarity. This allows the distal immobilizer 3964 tobe moved toward and away from the proximal immobilizer 3962. A flexiblejoint 3994 (FIG. 39A) is provided at the proximal immobilizer. Thisjoint 3994 can be any acceptable flexible coupling that hinges in twodegrees of freedom, including a section of flexible polymer material towhich the shaft 3982 is connected in the region of distal face of theproximal immobilizer 3962. It should be clear that a variety ofarrangements of linear motors consisting of magnetic members and coilsthat slide with respect to each other can be implemented according toalternate embodiments, within the general teachings of this embodiment.

Another inventive type of system for AGE actuation and steering is shownin FIGS. 40 and 41. The AGE 4010 in this alternate embodiment comprisesa proximal immobilizer 4012 and a distal immobilizer 4014 having anyacceptable vacuum hold-down arrangement to facilitate selectiveengagement to underlying tissue. Alternatively, a micro-needle hold-downarrangement of a type generally described herein, or another hold-downmechanism, can be provided. The central portion 4016 of the AGE 4010consists of pairs of disks 4020, one of which is shown in plan view inFIG. 41. Each of the disks 4020 opposes another disk. The number ofdisks 4020 is highly variable. Between the opposing disks, in oneexemplary embodiment, is provided a ring of flexible material 4030. Theflexible material 4030 provides elastic resistance to separation betweenthe opposed disks, and limits their outward expansion and maintainsrotational alignment therebetween. As discussed below in otherembodiments, disks can be held in alignment and expansion can be limitedusing other forms of guide mechanisms.

Each disk includes a plurality of electromagnets 4110 on each ofopposing faces thereof. The electromagnets are arranged so that whenthey are energized through wires 4050 (that extend along the cannula4052 to the control system), the magnets in opposing disks 4020 eachrepel or attract each other when electrically powered, and cause theelastic material 4030 therebetween to stretch. By energizing onlyselected of the electromagnets around the circumference of various diskpairs, the stretch occurs differentially, causing the overall middlesection 4016 to expand in a non-linear, non-axial (turning) direction.The electrical wires can be arranged to individually address certainmagnets, or groups of magnets in order to obtain the appropriate degreeof turn. Using known techniques, the control system can be adapted toprovide variable levels of voltage or current to selected magnets.

In an alternate embodiment, the flexible material between disks isomitted and the rigid disks are contained within a cannula or tubing (oranother alignment structure, such as guide wires) and move toward andaway from each other under alternate activated magnetic attraction orrepulsion. To conduct a flat turn in a first direction, for example, allmagnets at the depicted 9 o'clock position 4150 are made to repel, whileall magnets at the depicted 3 O'clock position 4152 are made toattract—and vice versa for a turn in an opposing, second direction.Climbing employs the 12 o-clock (4154) and 6 o'clock (4156) magnets.Magnets can remain aligned and maximum expansion can be limited by theguide wires, tubing, or other structures that pass through or along thedisks 4020. The number and placement of individual magnets about theperimeter is highly variable. In general the magnets should be placed sothat balanced turns can be achieved using the control system provided. Acontrol system may be adapted to provide variable power to variousmagnets to control the turn, or a more simplified control can employ anincremental (or simple on/off) voltage to the magnets.

It should be clear that in this, and other embodiments herein, usingmore conventional steering cables, that turning can occur not just alongone plane, but along orthogonal planes, thereby providing the full rangeof point ability to the distal immobilizer. This allows it to climb anddive, as well as to move left and right.

An orifice 4130, of appropriate size and shape is provided through thedisks, and through the proximal and distal immobilizers 4012 and 4014.This allows the therapeutic catheter 4060 to pass therethrough andreside therein. Also, as in other embodiments described herein, movementis accompanied by selective application of vacuum to each of theproximal immobilizer and distal immobilizer.

In operation, a typical movement cycle for the AGE 4010 would entailapplication of vacuum to the proximal immobilizer, while releasingvacuum on the distal immobilizer, causing expansion in the middlesection 4016 via electrical energy, reseating, by vacuum, the distalimmobilizer 4014, and then releasing the proximal immobilizer to allowthe elastic material 4030 to contract, thereby drawing the proximalimmobilizer forward. Differential energizing of certain magnets causesturning during the cycle and the resulting turn is finalized by securingthe distal immobilizer to the tissue by vacuum.

FIGS. 42-48 detail a variety of mechanisms that allow a proximalimmobilizer and distal immobilizer to be actuated and steered withvarious common elements. Each mechanism will be described briefly inturn. In FIG. 42, the proximal immobilizer 4212 and the distalimmobilizer 4214 are joined by a push mechanism 4220 that passesslidably through the proximal immobilizer, across a gap 4218, and thenagainst the proximal face 4222 of the distal immobilizer 4214. The pushmechanism 4220 extends back to the control system and can be actuated byhand or electromechanically by the user. By pushing forward (arrow4230), the distal immobilizer is moved forwardly relative to theproximal immobilizer. The proximal face 4222 of the distal immobilizer4214 includes a spherical surface that allows rotation (during steering)relative to the flattened end 4240 of the push mechanism 4220 within alimited range. The steering direction of the distal immobilizer 4214 iscontrolled by a plurality of steering cables 4250 that are selectivelypulled (arrow 4252) to provide steering (double-curved arrow 4260) tothe distal immobilizer 4214.

FIG. 43 shows an embodiment of a push-pull proximal immobilizer 4312 anddistal immobilizer 4314 that operate on principles similar to thosedescribed with respect to FIG. 42. In this embodiment, the distalimmobilizer includes a proximal concave well 4322 upon which the pushmechanism 4320 bears. This well allows a ball shaped distal end 4340 onthe push mechanism to rotatably engage the distal immobilizer 4314.Steering cables 4350 are pulled to orient the distal immobilizer 4314 inthe appropriate steering direction 4360 while the resulting ball (4340)and socket (4322) allow limited steering rotation.

FIG. 44 shows a proximal immobilizer 4412 and a distal immobilizer 4414according to another push-pull embodiment in which a plurality ofpush-pull mechanisms 4420 (typically, two, three or four separatepush-pull shafts) pass slidably through the proximal immobilizer 4412,and out through the proximal control system. The distal ends 4440 ofeach push-pull mechanism ride in a respective concave well 4422 thatallows for selective pushing and pulling (double arrows 4450) of any ofthe push-pull shafts 4420 to both advance the distal immobilizer 4414,with respect to the proximal immobilizer 4412 and angularly orient thedistal end in the desired steering direction. Orientation is achieved bypushing and/or pulling one push-pull mechanism 4420 a further or lesserdistance than other push-pull mechanisms. The rotation of the distalimmobilizer is taken up by the rotatable engagement between the wells4422 and distal ends 4440 of the push-pull mechanisms.

In the alternate push-pull embodiment of FIG. 45, the proximalimmobilizer 4512 and distal immobilizer 4514 are shown which a pair oflinear push-pull mechanisms 4520 are controlled (double arrows 4550) bythe control system. They pass through the proximal end and allow foradvancing of the distal immobilizer 4514 with respect to the proximalimmobilizer 4512. Steering is accomplished similarly to the AGEembodiment having the pivoting suction cup, as shown and described abovewith reference to FIGS. 31-33. The pivoting suction cup 4560 of thepresent embodiment rotates both the proximal and distal immobilizers4512 and 4514 as a joined structure based upon steering cables (notshown) that are anchored in the proximal immobilizer (similar to thoseof FIGS. 31-33).

FIG. 46 details a basic embodiment of a bellows-operated AGE with aproximal immobilizer 4612 and a distal immobilizer 4614 that are joinedby a plurality of selectively operable bellows 4620. Each bellows 4620is operated by a vacuum and/or pressure source at the control system.The bellows can be inflated together to advance the distal immobilizer4614 in a straight linear/axial direction (arrow 4630), or the bellows4620 can be individually operated to steer (double-curved arrow 4660)the distal immobilizer 4614 in any desired angular direction withrespect to the proximal immobilizer 4612. Various versions of thisimplementation are also shown in cross-section in FIGS. 25-28, describedabove.

In the exemplary embodiment of FIG. 47 a proximal immobilizer 4712 anddistal immobilizer 4714 are joined by a lead screw 4720 that extends outto a manual control 4730. The manual control allows the overall movement(arrow 4732) of the distal immobilizer 4714 with respect to the proximalimmobilizer 4712. In this embodiment the lead screw is flexible so thatmovement of steering cables 4750 while steering (double-curved arrow4760) of the distal immobilizer 4714. The hand-control 4730 can besubstituted for a motorized control as appropriate. This arrangement issimilar to that described above with reference to FIGS. 29 and 30.

Alternatively, as shown in exemplary embodiment of FIG. 48 the proximalimmobilizer 4812 and the distal immobilizer 4814 can be joined by asomewhat rigid lead screw 4820. Note that both lead screws 4720 and 4820typically engage a nut (not shown) embedded in the proximal end of thedistal immobilizer 4714 and 4814. In this embodiment, a flexible joint4840 allows the lead screw 4820 and distal immobilizer 4814 to pivottogether (double-curved arrow 4860) about the joint 4840. The distalportion of the drive shaft 4850 extends out to the control system whereit engages a geared drive 4870. Steering wires 4852 extend through theproximal immobilizer 4812 to join the distal immobilizer 4814 so thatsteering can be controlled by selective pulling on the steering wires4850 at the control system end. This arrangement is similar to thatshown in FIGS. 34-37.

It should be clear that a variety of other implementations for steeringand actuation can be implemented in accordance with this invention.

V. AGE and AID Steering Mechanisms

With brief reference to FIG. 49, a basic embodiment of an AGE 4910 isshown in bottom view for further reference steering mechanisms and otheroperative features. It includes a proximal immobilizer 4912, the distalimmobilizer 4914 and a sealed bellows 4916 there between. The sealedbellows receives vacuum pressure through an appropriate conduit, orother lumen. One vacuum lumen 4920 communicates with the vacuumhold-down port arrangement 4922 for the proximal immobilizer 4912. Anopposing lumen 4924 passes slidably through the proximal immobilizer4912 and communicates with a grid 4926 in the distal immobilizer. Eachlumen 4920 and 4924 can be separately depressurized and/or pressurizedto provide vacuum selectively to either the proximal immobilizer 4912,the distal immobilizer 4914, or both.

A set of steering wires (also termed “cables”) 4930 (three cables inthis embodiment) are disposed around the central lumen that includes theablation catheter 4950. The steering wires 4930 pass slidably throughthe proximal immobilizer 4912 and are anchored at an appropriate pointin the distal immobilizer 4914. Selective tensioning of the wires 4970allows the distal immobilizer 4914 to point itself of the central axis4970 in three dimensions with respect to the proximal immobilizer. Thewires 4930 are each located sufficiently remote from the central axis4970 of the device so that applying tension to one or more, whilereleasing tension from others induces a rotational moment about a pivotarea within the central region of the bellows 4916. In the embodimentsdescribed generally herein, the flexibility of the catheter comprisesthe “hinge” structure between the distal and proximal immobilizers. Thecatheter allows a gradual bend along the length between the immobilizersthat enables multidirectional steering without binding or kinking thecatheter. The degree of bending depends, in part, upon the amount ofcatheter length extending between the two immobilizers and the inherentbending characteristics of the catheter. This moment causes the distalimmobilizer 4914 to deflect angularly with respect to the proximalimmobilizer 4912. The wires 4930 can be constructed from any strong,relative small-gauge material, including a variety of monofilamentand/or braided polymers and metals.

The immobilizer in the above-described AGE 4910 uses a basic gridpattern to transmit vacuum. One advantage of a grid pattern is that itprevents excess tissue from being drawn into the vacuum chamber, whichmight serve to block the vacuum port and prevent effective hold-down. Apossible disadvantage to a grid, on curved or bumpy tissue, is that notall grid holes may be fully covered, allowing vacuum leakage andinadvertent release of the immobilizer.

VI. Immobilization

As described above, an immobilizer can be implemented in a variety ofways. FIGS. 50-52 detail an embodiment of a vacuum immobilizerarrangement that is particularly effective on highly curved surfaces.The exemplary AGE 5010 includes a proximal immobilizer 5012 and a distalimmobilizer 5014 that are steered and/or actuated by any of themechanisms described below. On the base of each immobilizer is a suctioncup 5020 and 5022. Each suction cup comprises a plurality of respectiveaccordion-like folds 5030 and 5032. These allow the respective suctioncup to compress as appropriate. The suction cup can be formed by anyacceptable, biocompatible flexible material that maintains a semi rigidstructure. The contacting base 5050 and 5052 of each suction cup cancomprise a differing material if desired. Such a material should havegood sealing properties and remain pliable against rough surfaces.Medical silicone is one such material.

As shown in FIG. 51 an exemplary suction cup 5020 is applied against arelatively curved tissue surface 5110. The suction cup 5020 is thenshown engaging the surface 5110 in FIG. 52. The base area 5050 of thesuction cup conforms to the shape of the tissue due to differentialflexure of the accordion folds 5030. The perimeter shape of the suctioncup in this example is somewhat ovular. In alternate embodiments, theshape can be more square, circular or any other desired shape.

FIGS. 53 and 54 detail an alternate arrangement for suction cups thatare applicable to either an AID or an AGE embodiment. In thisembodiment, a proximal immobilizer 5312 and a distal immobilizer 5314,joined by any conventional bellows-like or otherwise flexible centralsection 5316 each include a plurality of suction cups 5330. The suctioncups each comprise smaller versions of the cups 5020 and 5022 describedabove. In this embodiment, they are ovular, but they can be anyacceptable shape. They include a plurality of folds 5340 that allow thecups to comply with the surface texture and shape of the underlyingtissue. As shown more clearly in FIG. 54, each cup includes at least onevacuum port 5410 through which vacuum communicates with the individualcups. Appropriate lumens can be provided within the structure of theimmobilizers 5312 and 5314 to communicate vacuum selectively to theproximal and distal immobilizers. The cups can be constructed from thesame material as the underlying immobilizer, or can be a differentmaterial that is more suited to the pliability desired in a suction cup.

As noted above, larger cups may tend to draw thereinto tissue that mayserve to block a small vacuum port at the top of the cup. FIGS. 55-57show a suction cup having an anti-vacuum choke (AVC) for that feature.The immobilizer 5510 includes an integral cup chamber 5520. The catheter5530 passes through the immobilizer 5510. The large cavity of the cupmay tend to draw a bolus of tissue thereinto. Since the vacuum port 5540is relatively small, the tissue may easily block it if it issufficiently soft and pliable. Accordingly, a pair of raised disks 5550,or similar projecting structures, are provided as an AVC mechanism. Thedisks 5550 are placed relatively close to the port 5540 so that anypliable tissue drawn up by the vacuum will come to rest on the disks5550 and a gap region 5560 will remain between the disks or bosses 5550with any tissue bridging that gap. This gap region is sufficient forvacuum draw to be maintained around the tissue and into the adjacent cupvolume 5520.

As shown in FIG. 57, the angle of the inner wall 5710 of a cup interior5720 can aid in the appropriate delivery of suction and avoidance of anundesirable bolus. Also the larger the angle of this wall, the greaterlateral resistance to movement and slippage, which is more critical insome procedures such as an ablation. In this embodiment, the angle AC,combined with an AVC structure 5550, together assist in avoidingblockage of the port and cup interior by draw-in tissue. Hence, a propervacuum can be maintained. The angle AC is between approximately 40degrees and 90 degrees in various embodiments. However, the preciseangle can be determined by applying the cup to tissue similar to thatexpected to be encountered within the body. Often the tissue of a pig'sheart or other organ is a suitable model for human tissue of the sametype.

In another embodiment, not shown, the AVC feature is a fine materialmesh, generally the same size as the open face of the vacuum indentspace, which is away from the roof wall of the cup in roughly the samelocation as the projections 5550 above, to allow the vacuum to reach allparts of the vacuum indent space. The mesh forms the front surface of athin vacuum distribution chamber and the tissue is drawn tightly againstthe mesh instead of against the cup roof wall, thereby allowing for avacuum gap.

Another embodiment of an immobilizer vacuum base structure is shown forthe exemplary distal immobilizer 5812 of FIG. 58. In this embodiment, anelongated vacuum channel 5820 is provided near the outer edges of theimmobilizer 5812. A central region 5840, broken only by small ribs 5842(for structural integrity and stiffness) is provided beneath thecatheter lumen 5850. In this manner, the catheter 5860 is free to emitits ablation energy (or other therapeutic properties) through the openspace 5840 while substantial area for applying vacuum is afforded by thechannels 5820. The channels are fed by a vacuum lumen 5864 that passesthrough the central region 5870 proximally of the immobilizer 5812. Arespective pair of central vacuum chambers 5872 and 5878, locateddistally and proximally of the central open space 5840 provideadditional, centralized hold-down force in this embodiment. The centralvacuum chambers 5872, 5878 communicate through ports or passages (notshown) in the ribs 5874 located between the chambers 5872, 5878 and theside vacuum channels 5820. The channels are served by vacuum ports 5876that communicate with the vacuum lumen 5864. Appropriate steering cables5880 or other actuation/steering mechanism can also be provided tointerconnect with the proximal immobilizer (not shown). The proximalimmobilizer can employ the same, or a similar, base structure as thatdepicted in FIG. 58.

FIGS. 59-62 detail an alternate embodiment of an immobilizer that doesnot employ vacuum pressure to secure itself to tissue. It is recognizedthat small biocompatible needles and/or microneedles can be used tosecure materials to pericardial tissue and other forms of body tissuewithout incurring pain or irreparable damage. Such microneedles can beconstructed from biocompatible polymers, metals or ceramic materials.The micro needle material, for example, can be a standard biodegradablematerial or a biodegradable polymer, such as Polylactic Acid (PLA),Polyglycolic Acid (PGA) or others that may exhibit conductivity, whichis useful as an electrical sensor in determining the effectiveness ofthe ablation.

As shown in FIG. 59, an AGE 5910 of this embodiment includes a proximalimmobilizer 5912 and a distal immobilizer 5914. A catheter 5922 runsthrough the center of both immobilizers 5912 and 5914 and also through abellows region 5916 that provides appropriate steering and/or actuationto the distal immobilizer 5914. Such steering and actuation can be inaccordance with any mechanism described above. In this particularembodiment, the actuation is by means of two or more bellows 5924, whichcan each expand and contract individually. A pair of pressure lines 5950and 5952 extend, respectively, to each of the proximal immobilizer 5912and distal immobilizer 5914.

Referring further to FIGS. 61 and 62, within each immobilizer 5912, 5914is provided pairs of microneedle assemblies 5960 and 5962. When thepressure in either line 5950 or 5952 is applied, the respectivemicroneedle assembly 5960 and 5962 moves within a respective guideway6110 from a retracted position as shown in FIG. 61 to an extendedposition as shown in FIG. 62. In the extended position, the individualneedles 6210 extend outwardly beyond the plane of the base surface 6220of the immobilizer so that they engage the underlying tissue at an acuteangle AN. In this manner, upon needle deployment/extension theimmobilizer becomes essentially pinned to the tissue by large number ofsmall needles. The number of needles on an assembly can vary both in thelengthwise direction and in widthwise direction depending on thesize/diameter of the individual needles and the size of the needleassembly base 6130. The needle assembly base 6130 can includeappropriate seals or other structure that maintain a pressure sealbetween it and the guideway 6110. In this manner, the needle assembly isextended by pressurizing the guideway and the needle assembly isretracted by inducing a vacuum in the guideway. Appropriate sealsbetween the needle assemblies and the guideway prevent excessivepressure loss. To provide pressure/vacuum, each guideway 6110 caninclude appropriate ports 6150 in communication with a correspondingpressure lumen 5950 or 5952.

In an alternate embodiment, a push-pull linkage can be employed, actingon each assembly of needles in communication with an externally drivenlinkage. Likewise, electromagnetic energy could be used in, or along theguideway 6110 to actuate each array, which includes a magneticallyattracted base. In this manner, the needle bases act like solenoidsresponding to the force of an energized coil.

With reference to FIGS. 63-65 an alternate embodiment of a needle-basedhold-down mechanism is shown. As noted above under certain conditions,the underlying tissue surface may be irregularly shaped or rounded.Accordingly, a hold-down assembly can be constructed with a plurality ofindividual needle bases 6410 that are laid out in a longitudinaldirection (axially with respect to the direction of extension of theAGE). Each needle base 6410 can slide upwardly and downwardly separatelywith respect to adjacent needle bases. In one embodiment all the needlebases reside in a common guide way 6420, which is in communication withthe pressure/vacuum source. The needle sets are collectively sealedagainst air leakage and allowed to independently slide along theguideway. In one embodiment, the needle sets can be covered by a highlyflexible sealing membrane that, when inflated causes the needle sets toextend out of the base but prevents loss of pressure from the upperregion of the guideway adjacent to the port. In another embodiment thebases have a circular shape and are each placed sealingly in a separatecylinder this selectively filled with pressure/vacuum from a commonsource lumen to resultantly extend retract each of the bases to apredetermined distance.

When extended, all needle bases 6410 are driven to extend out of theplane base surface 6440 of the immobilizer and into the tissue surface6450. Notably, as shown in FIG. 65, because the bases 6410 areindependently moveable to varying distances, the application of pressurewill allow certain needle bases to extend further out (withinpredetermined limits that may be set by a stop) than other adjacentbases. Hence, as shown in FIG. 65, a tissue surface 6510 that islongitudinally curved can be fully engaged. To this end, the outermostbases 6520 have extended further downwardly than the innermost bases6540 to conform to the downwardly sloping curve of the tissue surface6510. The extension pressure should be chosen so that it allowsdifferential extension of different needle sets without forcing allneedle sets to extend to a maximum distance. This ensures that the unitwill gently conform to the shape of the tissue without applyingexcessive force to it. As shown in this embodiment, a plurality ofneedles have been laid across both the lengthwise (longitudinal) and thewidthwise directions of each set. The precise number of needles, theshape of each set base, the size of individual needles and otherparameters are highly variable.

Note that in each of the above-described micro needle embodiments, oneadvantage is that the needles may be electrically interconnected withleads that extend back to the control system. In this manner, theneedles can be used to apply energy or measure temperature or othercharacteristics of the tissue. This may help to determine the efficiencyof the ablation process or to perform other diagnostic functions. Inaddition, the needles may include microscopic lumens through whichmedicines and other fluids can be applied to the surface. In any of theembodiments above, it is expressly contemplated that fluid conduits thatprovide cooling fluid or other desired gases or liquids can be includedin the distal and/or proximal immobilizers or in any appropriate AIDstructure.

Another embodiment of an inventive hold-down mechanism is shown in FIG.66. In this embodiment, an AGE 6610 similar to the type shown in FIGS.29 and 30 (although any AGE or AID can be employed herewith) is appliedto the heart 6620. The proximal cannula 6630 extends back out of thebody to the control system. The AGE includes any desired steering and/oractuation mechanism such as the helical drive 6640 shown herein. On thetop side of the proximal immobilizer 6612 is provided an inflatableballoon 6670. A similar balloon can be provided on the distalimmobilizer if desired. Pressure send through the cannula 6630 causesthe balloon to inflate when desired. Since the heart is in closeproximity to other organs or tissue 6672 within the body cavity, it iscontemplated that inflation of the balloon 6670 will bring it intoengagement with the tissue or organ 6672 as shown. This assists inholding down the immobilizer against underlying tissue, and may avoidthe need for internal vacuum chambers, microneedles and/or otherhold-down mechanisms that must engage the underlying tissue (and mayblock access to the catheter). Additionally, by creating and maintaininga space between the target tissue, such as the heart, and surroundingorgans during ablation, the chance of injuring surrounding regions areminimized. Alternatively, this balloon 6670 can be used to supplementsuch mechanisms where desired.

VII. AGE Control System

Reference is now made to FIG. 67 that shows an overview of the controlsystem for an exemplary implementation of the AGE according to anembodiment of this invention. Reference is also made to the moregeneralized block diagram of more generalized control system functionsshown in FIG. 68. In each diagram a microwave generator 6610 is shown.The generator is used to transmit the desired level of microwave energyto the above-described ablation catheter. Note that other forms ofablation can be employed according to this invention. Such forms ofablation include regular and light-based catheters, those that useelectrical contact to cauterize tissue and cryogenic fluid-deliverysystems. An appropriate energy/fluid generator for such types ofcatheters could be substituted for the microwave generator 6710. In thisembodiment, the microwave generator transmits energy through a line 6712contained within the cannula of the catheter. The catheter extendsthrough the body interface 6820 (FIG. 68), namely skin and muscle layerscovering the thoracic cavity, and into the interior of the body wherethe operative end of the exemplary microwave catheter 6730 residesduring the procedure.

The microwave catheter 6730 is carried by the ablation guidance enhancer(the AGE 6740) in this embodiment. The AGE. 6740 is controlled by acontrol system and user interface 6750 that receives air and vacuum froma source 6752 via the line assembly 6754. This line assembly includes,typically, a separate air line 6756 and vacuum line 6757 routed fromappropriate pumps within the source 6752. Within the control system iscontained a set of valves that control the hold-down function as well as(in this embodiment) the actuation function which is carried out by abellows actuator 6760 located between the proximal immobilizer 6762 andthe distal immobilizer 6764. As shown, a proximal vacuum valve 6770controls the hold-down of the proximal immobilizer via a proximal vacuumline 6772. When this valve is opened, vacuum is applied to the proximalimmobilizers vacuum chamber 6774. A distal vacuum valve 6776, also incommunication with the main vacuum line 6757, can be opened to provide avacuum to the distal immobilizer's vacuum line 6778. When opened, thedistal immobilizer's vacuum chamber 6780 is placed under vacuum pressureallowing it to act as a hold-down.

The user coordinates (or a computer/processor automatically coordinates)the actuator's (6760) advance and retract valves. The advance valve 6782and retract valve 6784 are each in communication with a separate linesource 6756 and 6757. They both communicate with the bellows actuatingline 6786. When the retract valve 6784 is opened, the vacuum source isconnected with the bellows line 6786, allowing vacuum to draw thebellows together. Typically this occurs while the distal immobilizer isheld down and the proximal immobilizer is released, thereby allowing theproximal immobilizer to crawl forward. Conversely, when the proximalimmobilizer is held down, and the distal immobilizer is released, theretract valve 6784 is closed and the advance valve 6782 is opened,allowing a predetermined amount of air pressure to enter the bellows6760. Once the bellows is fully extended the distal immobilizer is againheld down. While not shown, either within the vacuum source, or alongeach line, is provided appropriate pressure release and pressuremonitors that prevent excessive buildup or either pressure or vacuum.Such buildup could cause failure in the device due to overstressing.

In this embodiment, a wire or cable-type steering arrangement isprovided. Four cables located in quadrants around the AGE 6740 areemployed. The cables are typically placed under moderate tension alongthe entire length of the cannula run to avoid play in the steering dueto slackness. Automatic slack-removal devices, such as spring assembliesor electromechanical actuators (not shown) can be employed to maintainand regulate the desired level of tension. In this embodiment the foursteering cables comprise an up cable 6790, a down cable 6792, a leftcable 6794 and a right cable 6796. However, in some embodiments threecables oriented at approximately 120 degree angles to each other canalso be employed with appropriate mixing of control functions. Withinthe center of the cable arrangement is an electromechanical ormechanical joystick 6798.

The joystick assembly is shown in further detail in FIG. 69 inaccordance with one exemplary embodiment. The embodiment includes acontrol stick 6910 located on a ball mount, or other gimbal system 6920.The cables 6930 are each interconnected to bases 6932 at each of fourcorners 6934 (or other structures) on the joystick plate 6940. As shownthe cables remain under tension and eventually neck down through anarrowed opening 6950 in the control unit to eventually comprise atensioned cable run 6960 within the catheter assembly 6970. Tension canbe maintained by ensuring that, at no point along their run, the cablesare allowed to become loose. Appropriate adjustment screws, turnbucklesand other devices can be provided to the joystick assembly to ensurethat the cables remain taut and properly adjusted for center.

FIG. 70 shows a schematicized example of a control panel 7010 that canbe employed in connection with AGE and in accordance with thisinvention. A display 7012 provides status data and other informationwith respect to the operation of the AGE. For example, it can provideindicators as to which hold-down is currently operating and the steeringdirection in which the AGE has been placed. Buttons 7020 the vacuumhold-down function of the proximal immobilizer as shown, as well asbuttons 7022 that control the vacuum hold-down function of the distalimmobilizer. A joystick 7030 of a type described generally in FIG. 69for mechanically controlling the steering cables is provided at thecenter of the panel 7010. Alternatively, the joystick 7030 can interfacewith various electomechanical, pneumatic, hydraulic or electromagneticcircuits so as to control AGEs that operate on such principals, in amanner described generally herein. A pair of slide switches 7040 and7042 are used to advance or retract the actuator so that the immobilizermoves in a proximal direction (switch 7040) or a distal direction(switch 7042).

It should be clear that the control panel described herein is onlyexemplary, and that various hardware and software components can be usedto coordinate movements of components. Likewise, the control mechanismshown herein can be provided on a computer screen, such as thatavailable in a laptop and/or desktop PC configuration. Appropriateinterfaces can be provided between the computer and its control softwareand the underlying mechanical components that operate the catheter. Inthis manner, movement of the catheter can be fully automated and largelyunder the control of the computer. In one example, when the userinstructs the AGE to move forward by a certain amount, the computerautomatically activates the hold-down vacuum in one immobilizer,advances the other immobilizer, and then activates the hold-down vacuumin the advanced immobilizer. When the user instructs a turn, thecomputer automatically applies an appropriate amount of steering in thedesired direction to the cables or other steering devices. Electrodeswithin the AGE's base can indicate when a maneuver has been completedcorrectly.

Reference is now made to FIG. 71, which shows an embodiment of apressure circuit used in connection with a bellows-based actuation (andsteering) system for an AGE 7110. The AGE 7110 includes proximalimmobilizer 7112 and a distal immobilizer 7114. These immobilizers 7112,7114 are joined by two or more discrete bellows 7116 each communicatingwith its own pressure lumen 7120 and 7122. In this embodiment, bothlumens 7120, 7122 are joined to a common pressure feed lumen at aY-connection 7124. However, the in another embodiment, two or morecircuits of the type described in FIG. 71 can be employed together tocontrol each respective bellows separately so as to provide steeringcontrol as well as actuation.

A pump 7130 is provided in the system. This pump delivers both pressure(arrow P) and vacuum (arrow V) simultaneously through opposite outlets7132 and 7134, respectively. Alternatively separate pressure and vacuumpumps can be provided at each outlet. In the depicted embodiment, eachoutlet 7132 and 7134 contains an appropriate two-way valve 7136 and7138, respectively. Either valve is closed when desired to place eitherpressure or vacuum into a pressure control circuit 7140. When a valve7136, 7138 is open, it vents to the atmosphere via an associated vent7142 (for vacuum) and 7144 (for pressure). Only one valve 7136, 7138 isclosed into the circuit 7140 at a time. In this example, the pressurevalve 7136 is closed while the vacuum valve 7138 vents to atmosphere. Apressure regulator 7150 is provided along the pressure line 7152 of thecircuit to avoid overpressure within the system. A two-way valve 7160 isprovided at the feed line 7162 to the two lumens 7120 and 7122. Asshown, the valve 7160 is arranged so that the pressure line 7152 is incommunication with the lumens 7120 and 7122. In the depicted circuit7140, the bellows are pressurized. In an alternate position shown in thecircle 7170, the valve 7160 is rotated so that the pressure line isvented to atmosphere via the vent 7172. The lead 7162 to the lumens 7120and 7122 is placed in communication with the vacuum line 7176 of thecircuit 7140. In order to deliver a vacuum, the outlet valve 7138adjacent the pump 7130 is rotated so that the vacuum outlet 7134 isplaced in communication with the vacuum line 7176. In that orientation,the lumens receive vacuum and the bellows contract.

By maintaining the valves in the appropriate positions, a continuouslyoperating pump can deliver pressure, vacuum or neither to the bellows asdesired. It should be clear but by simply duplicating the circuit 7140and associated valves, that a plurality of bellows can be operatedindependently at each lumen. This alternate arrangement is expresslycontemplated to provide steering as well as actuation. As describedabove, while AIDs are not capable of independent movement, they can besteered to place them into a desired position, once directed to anapproximate location on the tissue.

VIII. Improved AID Structures

As shown in FIG. 72, a moving-floor embodiment of an AID (or AGE) 7210includes an outer omega-shaped/arched body 7212 with a lumen 7214 forreceiving a catheter. The arch-shaped upper structure of the AIDincludes three cable anchors 7220 for steering cables that extendthrough associated lumens 7224 (shown in phantom) within the structureof the AID body 7212. A sliding floor 7230 is provided at the base ofthe lumen 7214. The sliding floor rides on ribs 7232, which are keyed sothe Omega arched structure 7212 cannot separate and dislodge the floor7230, face each other near the base (suction base) 7240 of the AID 7210.In order to affect better steering, the base also includes a steeringcable anchor 7250. An associated steering cable (lumen 7252 shown inphantom) extends back through the floor. The steering cable exertstension on the floor when steered. As the floor is pulled away, thetable is drawn out with it as steering is no longer needed while the AIDis immobilized. By sliding away the floor it is allows the bottom of thelumen to be exposed to the tissue so the catheter can be more closelybrought into proximity with the tissue. In an alternate embodiment, aninternal catheter lumen-mounted hold-down balloon or bladder can beprovided—such as the balloon (1670) shown and described with referenceto FIGS. 16 and 17.

Reference is now made to another embodiment of an AID 7310 shown inFIGS. 73 and 74. The AID encases a therapeutic (typicallymicrowave-ablation) catheter 7320, and includes a series of openhold-down segments 7330 that are separated by a predetermined distance,and are each connected by a portion of a vacuum line 7332. The vacuumline 7332 places each segment 7330 into communication with the vacuumsource, and also into communication with a more distal vacuum-linesegment that transmits the vacuum along the segment line (except for themost-distal segment, which is sealed at the end). The spacing betweensegments 7330 is highly variable. While not shown, independent steeringcables can be provided between cables to steer the unit. Alternatively,it can be steered into position using a steerable guide catheter thathas been removed, allowing the segments to be held in place by vacuum.Alternate hold-down mechanisms as described above, such as theneedles/microneedles or the compressing balloon can also be used with,or instead, of vacuum.

As shown further in FIG. 74, a pair of vacuum ports 7420 are provided onthe base of each segment near the respective outer edges thereof. Thelumen 7430 is opened, defining a somewhat horseshoe-shape in each of thesegments 7330. This relatively open base allows the full area of thecatheter to be exposed to the underlying tissue. Each segment's vacuumports 7420 can be constructed in a variety of ways. They can beconstructed as a plurality of small ports, suction cups, or any of theother types of vacuum immobilizer base structures described herein.

Another embodiment of an AID 7510 is shown in FIGS. 75-77. In the bottomview of FIG. 75, the AID comprises a semi-circular-cross-section (orD-shaped) housing 7520 with an internal lumen sized and arranged toreceive a catheter. The elongated side bases 7530 of the AID bottom eachinclude a series of elongated ports 7532 in communication with a vacuumlumen 7610 as shown further in FIG. 76. A set of steering wire lumens7620 are provided around the semi-circular portion of the housing 7520.Associated steering wire anchors 7720 (FIG. 77) are provided at thedistal end 7722 of the AID housing 7720. The steering wires 7620 extendproximally from these anchors, and eventually terminate at the controlsystem. At various locations along the length of the AID bottom, astrengthening rib 7560 ties the two sides 7530 of the bottom together.This prevents the opposing elongated side bases 7530 of the AID fromsplaying apart along the AID's midsection. However, this ribbed bottomconfiguration still allows this sufficient area for the enclosedcatheter to be exposed to the underlying tissue.

With reference now to FIGS. 78-80, another embodiment of an AID 7810 isshown. This AID includes a tissue-engaging bottom with side edges 7820and a semi-circular or D-shaped structure 7820 that defines an openlumen 7822 for receiving a therapeutic (for example, ablation) catheter.A series of openings 7830 are provided along the center of the bottom.These openings 7830 define vacuum ports 7920 that communicate with a setof lumens 7922 extending from the side edges of the structure. Theablation catheter transmits energy through the bottom wall 7940. Thewall 7940 is constructed from material having sufficient resistance, orsufficient transmissivity to microwave energy so that the energy passesefficiently into the underlying tissue. This structure has the advantageof maximizing hold-down engagement in the area of the tissue in whichthe microwave energy actually emits.

IX. Distal Immobilizer-Mounted Minimally Invasive Surgical Tools

While the various AGEs described herein are contemplated for use withablation procedures, other forms of minimally invasive surgery can beundertaken using, for example, the AGE immobilization, steering and/oractuation mechanisms described herein. It is contemplated that thedistal immobilizer (or the proximal immobilizer in certain embodiments)can be adapted to carry a variety of surgical tools for performingprocedures other than ablation.

FIGS. 81 and 82 show an embodiment of the distal immobilizer 8110 of anAGE (or AID in some implementations) that contains a vacuum immobilizerchannel 8120 according to any embodiment herein. Another type ofimmobilizer mechanism, such as a microneedle-based, hold-down system,can be employed in an alternate embodiment.

The exemplary immobilizer 8110 is adapted for performing biopsyprocedure on internal tissues. The immobilizer 8110 includes apneumatic, hydraulic, electromechanical or mechanically operated cutterassembly 8130 within its housing. The cutter assembly 8130 with a cutterblade 8132 that extends into a vacuum extraction port 8134 uponactivation of a linkage 8136. The cutter can be operated alternatively,by pressure and/or vacuum, a mechanical linkage or electromechanicalenergy, such as a solenoid. As shown in the front cross section, thedissection channel is, in fact, located along the center of the bodywhile the two immobilizer channels 8120 are located on opposing sidebasis so as to remain separated from the dissection channel. Vacuumlumens 8220 are provided for each hold-down. In operation, theimmobilizer is placed over an area to be separated from a drawn-in bolusof tissue, and the severed tissue is drawn into the tissue-extractionport 8134. The blade 8132 moves forward when the tissue is in place tocut it off and draw it to the port 8134.

Another embodiment of a distal immobilizer 8310, which can be used inconjunction with minimally invasive surgery, is shown in FIGS. 83-84.The distal immobilizer 8310 in this embodiment is adapted to performtissue-dissection procedures. It also includes immobilization vacuumchannels 8320 that are disposed along the sides of the base. A centralvacuum tissue channel 8330 is located to extract tissue that is actedupon by a cutting knife 8340. The knife moves downwardly (as shown inphantom in FIG. 83) under operation of an actuator 8350. In oneembodiment, the actuator is a pneumatic actuator. Alternatively, theactuator can be implemented as a mechanical actuator, joined by apush-pull linkage to the control system, for engagement by the user, oran electromechanical actuator such as a solenoid. The dissection knife8340 moves downwardly below the plane of the base (as shown in phantom)to slice underlying tissue. Any detritus can then be extracted thoughthe vacuum tissue port 8330. This distal immobilizer 8310 is effectivein any dissection operation to be performed minimally invasively.

FIGS. 85 and 86 detail another type of minimally invasive instrumentconstructed within a distal immobilizer 8510. The associated vacuumimmobilization, and other mechanisms, have been omitted for simplicity.Any of the above-described immobilization structures can be employed, aswell as any appropriate actuation and/or steering mechanism. Theinstrument of this embodiment can also be used in conjunction with AID,which omits an actuation and/or steering function.

The depicted immobilizer 8510 includes a needle-guide lumen 8520 intowhich is mounted an elongated, flexible needle 8522 with a central lumenfor delivery of fluid. The distal end 8524 of the lumen 8520 is angledat an acute angle AL with respect to the base 8526. The angle AL can bebetween approximately 10 degrees and 75 degrees in an illustrativeembodiment, but the angle can be highly varied in alternate embodiments.The needle 8522 is also angled to a conventional chisel point at itsdistal end to assist entry into tissue. The needle 8522 can beconstructed from any biocompatible material including a resilientpolymer or a memory metal such as Nitinol. It includes an appropriatetip 8530 for incursion into tissue 8532. The needle 8522 communicateswith a proximal fluid lumen 8540 that can be connected to a conventionalfluid-introduction coupling outside the patient. Alternatively an arrayof microneedles could be used instead of a single needle to deliverfluids as described in the embodiment below.

Once the immobilizer 8510 is held down to the tissue 8532, as shown inFIG. 86, the needle can be driven forwardly (arrow 8610) into the tissue8532. The bend in the needle-guide lumen 8520 causes the needle 8522,which is constructed from flexible metal, to also bend as shown that itenters the skin at the approximate angle AL. In this manner, the needle8522 does not pierce at a normal (perpendicular) angle to the tissue,which may cause it to puncture a thin membrane. Rather, the needle 8522extends sideways into the tissue, with less chance of puncturingcompletely through an underlying membrane. In the case of thepericardium, this undesirable effect could cause a needle to puncturethe heart. Once the tissue is pierced by the needle 8522, an appropriatefluid can be delivered through the fluid lumen 8540 to exit the hollowtip 8530.

In FIGS. 87 and 88, another distal immobilizer 8710 is shown immobilizedon tissue 8720. The needle 8730 resides within a lumen 8732 thatincludes a rounded distal-most wall 8740. The needle end 8742 isnormally directed downwardly (being formed from a memory metal, orsimilar-property material) so that is substantially normal to the base8750 and underlying tissue. When the needle is driven distally (arrow8810 in FIG. 88) the needle drives downwardly (arrow 8820 in FIG. 88),substantially normal/perpendicular into the underlying tissue 8720 asshown. Hence, the axial, distally directed movement of the needle 8522causes it to engage the curved wall 8740 and drive downwardly into thetissue 8720 as shown in FIG. 88. Fluid can, thus, be delivered deeperinto a tissue in this embodiment when such deeper distribution of amedicament is appropriate. A variety of other geometries and structuresfor allowing hypodermic needles to be deployed into tissue for deliveryof medicaments or other diagnostic purposes (at an appropriate entryangle) can be employed in accordance with alternate embodiments.

As described above, rather than a single needle, an array ofmicroneedles can be specially adapted to deliver fluid to tissueaccording to an alternate embodiment. This arrangement is advantageousin that is combines hold-down and fluid-delivery functions, limitsover-penetration into thin-walled tissue and spreads the medicament overa wider area with better dilution so as to limit overmedication of asingle point. FIG. 88A shows a distal immobilizer 8830 that is part ofan AGE having actuation and steering mechanisms in accordance with anyof the above-described embodiments herein. The immobilizer 8830 includesa cavity 8832 that is adapted to store a plurality of microneedle ormicrospike assemblies 8834. A vacuum or other immobilization mechanismis provided along part of the base 8836 of the immobilizer 8830. In thisembodiment, the microneedles are designed for implantation to tissue,rather than use as an immobilization mechanism. However, the teachingsherein can be applied to fixed, hold-down immobilizers as describedabove. In other words, the electronic interconnections and fluidinterconnections used in association with these immobilizers can bemodified to operate with a fixed, hold-down embodiment of a microneedlearray.

As shown further in FIG. 88D, a typical microneedle assembly 8834 isfurther detailed. In this embodiment, the assembly 8834 includes a base8836 that can be constructed from a biocompatible and/or biodegradablematerial. Biodegradable materials allow for eventual reabsorbtion of thearray without need to surgically remove it when no longer needed. On thetissue-engaging bottom 8838 of the assembly 8834 is formed a microneedleor microspike arrangement 8839. In accordance with FIG. 88A, adriveshaft 8840 is driven distally (arrow 8842) so that its ramped face8844 engages an opposing ramped face 8846 on an anchoring shaft 8848that rides within a vertical guideway 8850 that opens onto theunderlying tissue 8852. When moved distally 8842, the engagement of thefaces 8844 and 8846 causes the anchoring shaft to move downwardly (arrow8854) into the underlying tissue surface. 8856. As shown, a distal-mostmicro needle or micro spike assembly 8860 has been deposited in thetissue surface 8856. This, and other discrete assemblies 8834, arestored within a chamber 8862 beneath the shaft 8840. Each assemblyincludes a wire or tube 8870 that communicates through the cannula withthe control system. These tubes allow delivery of electrical signals orfluid as appropriate. When the assembly 8834, 8860 is implanted in thetissue 8856, it remains embedded therein with its needles 8839 inengagement with the tissue surface. This interconnection allows thedelivery of fluid and/or electrical signal transmission with respect tothe tissue surface from a remote location at the control system.Appropriate interfaces at the control system can be employed accordingto those of ordinary skill for each form of interconnection. When anassembly 8860 is deposited, the next assembly in line (microneedleassembly 8872 in this example) can be moved distally (arrow 8874) tolocate it beneath the anchoring shaft 8848 for implantation. Anappropriate advancing mechanism (such as a push-rod activated at thecontrol system and extending though the cannula—not shown) can be placedbehind the proximal-most assembly to drive the group of assembliesdistally.

It is contemplated, that the implanting distal immobilizer (or proximalimmobilizer in alternate embodiments) comes prepackaged with theappropriate microneedle assemblies. Briefly, a fluid-delivery assembly8880 is shown in further detail in FIG. 88C. Beneath the assembly'shousing 8882 is provided a hollow fluid reservoir region 8884. Thisreservoir 8884 communicates with hollow microneedle tubules 8886 havingopen tips 8888. An appropriate channel within the housing 8882 allowsfluid to be transferred from the attached tube (8870) to the reservoir8884. The structure of the microneedle assembly 8880 can be fabricatedin a variety of ways. For example, the microneedles can be constructedon a substrate of metal, silicon or another material using conventionalphotolithography processes.

A conductive, signal-transmitting microspike assembly 8890 is shown inFIG. 88D. This structure consists of a conductive metal base 8892 thatis provided within the housing 8894. The spikes 8896 are individualsegments of the metal plate 8892 that have been etched or otherwise cutinto the pointed shape as shown, and then folded along their remainingconnection with the metal base 8892 into the downwardly directedorientation as shown. The spikes 8896 can be cut on three sides as shownusing photochemical-etching or laser-cutting techniques, among otherforms of known manufacturing processes. It should be clear that avariety of manufacturing techniques and structures can be used to formeither micro needles or micro spikes according to further embodiments.

In accordance with the teachings of this invention an AID or AGE can beprovided with an integral ablation mechanism, or any other therapeuticdevice, rather than a removable catheter positioned in a conforminglumen. The distal end, for example, can include an integral ablative tipthat moves across the subject tissue with any power leads that energizethe tip extending through the cannula to the control system.

Reference is now made briefly to FIGS. 89-91, which show a generalizedproximal immobilizer for use with a drive helix-actuating arrangement.The proximal immobilizer 8910 includes a central vacuum chamber 8920that communicates with vacuum lumens 9010 (FIG. 90) a central lumen 8930receives the catheter 9110 (FIG. 91). Another lumen 8940, above thecentral lumen 8930 receives the drive shaft 8950 (shown in phantom) anda flexible joint 8960 that resides within an enlarged chamber 8962. Thehelical drive extends outwardly from the chamber on the shaft 8964 (alsoshown in phantom). As shown in the cross section 90, four steeringlumens 9030 are also provided around the structure. In FIG. 91, theassembled proximal end of the immobilizer 8910 is shown with the bellowscannula flange seal 9150 in place.

FIGS. 92-95 show a distal immobilizer 9210 according to an alternateembodiment. The immobilizer includes a vacuum chamber 9220 having aplurality of vacuum ports 9222 beneath a lumen 9230 for a microwave orother catheter. Each vacuum port 9222 interconnects with a vacuum lumen9240. A set of steering cables are provided within steering wire lumens9250. In this embodiment, there are three steering wire lumens 9250.However any appropriate number of lumens and associated wires can beemployed in connection with the teachings of this invention.

An external anchor 9255 for one of the steering wires can be viewed inFIG. 92. In this embodiment, three string cables are used, but fewer ormore can be employed in alternate embodiments. Notably, another lumen9260 is located beside the top steering cable lumen. This lumen 9260communicates with a pressure source located at the control system. Thelumen 9260 attached to a bladder or balloon 9270 located within the topof the catheter lumen 9230. When the catheter is positioned within thelumen, the balloon 9270 can be inflated to secure the catheter in placeagainst the bottom surface 9450 of the catheter lumen 9230. In thismanner, the distal immobilizer 9210 provides an effective hold-downmechanism for a catheter or other device inserted into a body cavity.

It should be clear that the foregoing devices provide a wide variety ofmechanisms for control, immobilization, manipulation and application ofa microwave ablation catheter and other therapeutic devices. It shouldalso be clear that any of the concepts described herein can be combinedwith other concepts to construct further embodiments that are notexpressly shown or described herein. It should also be clear that theAGE, AID and related components described herein can be constructed froma variety of commercially available materials with biocompatiblecharacteristics where appropriate. These materials can be rigid,semi-rigid or flexible/pliable as appropriate to those of ordinary skillin designing such components. The wall thickness for various structuresare highly variable and depend, in part upon the size of any lumenspassing therethrough, the strength of the chosen material and theoverall size/diameter of the device. Such thicknesses can be in therange of one millimeter or less, up to several millimeters. Structurescan be formed using a variety of techniques including machining of stockmaterial, molding and rapid-prototyping.

The foregoing has been a detailed description of illustrativeembodiments of the invention. Various modifications and additions can bemade without departing from the spirit and scope if this invention. Eachof the various embodiments described above may be combined with otherdescribed embodiments in order to provide multiple features.Furthermore, while the foregoing describes a number of separateembodiments of the apparatus and method of the present invention, whathas been described herein is merely illustrative of the application ofthe principles of the present invention. For example, the materialsemployed for the various components herein are highly variable, and canbe combined in many ways to provide appropriate characteristics adaptedto the particular therapeutic goal. The shape and size of a containedcatheter can be highly variable, and the AID or AGE can include a lumenparticularly sized and shaped to accommodate the catheter. The externalperimeter shape of the AID or AGE can be adapted to the desired deliverysystem, including a trocar, guiding catheter or guidewire. Also, thesedevices herein can be fitted with a variety of devices and sensors formeasuring characteristics of the contacted tissue and body cavityincluding, but not limited to heart sensors, temperature sensors andminiature (fiber optic) cameras, which can be placed in conjunction withthe catheter or surgical tool to provide appropriate readings of thesurrounding area. Also, it is expressly contemplated that any of thedevices described herein can be adapted to be employed on any internalorgan or tissue structure. Variations in size, shape and othercharacteristics needed to adapt a device to such a task should beapparent to those of ordinary skill. Likewise the introduction systemand location can be adapted to reach such an organ or internal locationusing techniques known to those of ordinary skill. Accordingly, thisdescription is meant to be taken only by way of example, and not tootherwise limit the scope of this invention.

What is claimed is:
 1. A method for ablating a target tissue in apatient's body, the method comprising: providing a device comprising anablation catheter comprising an ablation element; and an immobilizermechanism coupled to the ablation catheter, wherein the immobilizermechanism is distal to the ablation element, is configured to anchor thecatheter and to axially pull the ablation element toward the immobilizermechanism after the immobilizer mechanism is engaged; inserting thedevice into a patient's body; immobilizing the device within thepatient's body; axially pulling, via the immobilizer mechanism, theablation element to contact to a target tissue while the immobilizermechanism is engaged; and ablating a surface of the target tissue. 2.The method according to claim 1, wherein the target tissue is cardiactissue.
 3. The method according to claim 1, wherein the ablationcatheter is a radiofrequency ablation catheter.
 4. The method accordingto claim 1, wherein the device is steerable.
 5. The method according toclaim 1, wherein the immobilizer mechanism comprises an electricalconductivity sensor.
 6. The method according to claim 5, wherein theelectrical conductivity sensor can verify that a therapeutic ablationhas been delivered.
 7. The method according to claim 1, furthercomprising a locking mechanism that is configured to lock the ablationcatheter axially in place.
 8. The method according to claim 1, whereinthe device further comprises a control system operably coupled to thedevice.
 9. The method according to claim 8, wherein the control systemcontrols an amount of energy transmitted to the ablation catheter. 10.The method according to claim 7, wherein when the locking mechanism isengaged, the ablation element maintains contact with the target tissueduring ablation.